JP2000278877A - Information processor provided with function to charge secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an efficient charging control by a method wherein when the maximum consumed current of an information processor is lower than an allowable charging current of a secondary battery, the output of an AC adapter is supplied within a range not exceeding the maximum value of the charging current to be proportionally divided for the information processor and the secondary battery, and constant-voltage charging is performed when the battery comes close to a full charged state. SOLUTION: From a vacant to a specified charging state of a secondary battery 13, a constant-voltage constant-current controlling section 15 controls so that the output of an AC adapter 11 may be constant current. When charging moves on and the terminal voltage increases to a specified value, it is judged that the battery is going up a full charged state and thereafter, the AC adapter 11 is switched to a constant-voltage operation. If the maximum consumed current of an information processor 12 is lower than an allowable charging current of the secondary battery 13 and a charged amount of the battery is smaller than a full charged amount, the output of the AC adapter 11 is controlled to the allowable charging current value. The output is proportionally divided for the information processor 12 and for charging of the secondary battery 13. When the secondary battery is going up a full charged state, charging is switched to a constant-voltage charging to prevent overcharging of the secondary battery 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus having a function of charging a secondary battery, which operates using the secondary battery as a power source when the mobile phone is carried.

[0002]

2. Description of the Related Art In recent information processing apparatuses, a lithium ion secondary battery which has a high capacity density and is not affected by a memory effect is used as a power supply. The charging method of the secondary battery is controlled such that constant current charging is performed during charging from an empty state and charging is performed quickly, and switching to constant voltage charging is performed when full charging is approached to prevent overcharging. The charging of the secondary battery and the supply of power to the information processing apparatus as a load are performed after stepping down from a commercial power supply to a direct current using an AC adapter.
In order to realize a small size and low cost, the AC adapter can supply the maximum current consumed by the secondary battery and the information processing device, but cannot supply the maximum current at the same time.
Therefore, when charging while operating, the secondary battery is charged with the remaining power after consumption by the information processing device. Specific implementations of these are described in US Pat.
No. 98,964 is known.

FIG. 5 is a block diagram of a conventional charge control method, in which 52 is an information processing apparatus serving as a load, 53 is a secondary battery that supplies power mainly when the mobile phone is carried, and 54 is a battery that supplies current to the secondary battery. This is a backflow prevention diode for preventing backflow. Reference numeral 56 denotes a current detection unit that detects a current supplied by the AC adapter, 58 denotes a voltage detection unit that measures a terminal voltage of the secondary battery, 59 denotes a charging current detection unit that detects a charging current to the secondary battery, and 55 denotes a constant. The voltage constant current control unit and the control unit 57 control charging of the secondary battery so as to perform constant voltage constant current charging. An AC adapter 51 supplies power to these circuits.

When the information processing device 52 is stopped or in a suspended state, when it detects that the voltage indicated by the voltage detecting unit 58 is low and the battery is not fully charged, the constant current allowed by the secondary battery based on the value of the charging current detecting unit 59 is used. Charge by value. As a result, charging can be performed in a short time, and when the voltage detection unit 58 detects that the full charge is approaching due to the increase in the terminal voltage, the constant-voltage / constant-current control unit 55 switches to charge at a constant voltage.
Thereby, charging is performed until the battery is fully charged, and overcharging is prevented. FIG. 6 shows the relationship between the charging voltage, the charging current, and the constant voltage control in full charge.

While the information processing apparatus 52 is operating, the constant voltage / constant current control is performed in the same manner. However, the value of the charging current detector 59 limits the charging current to a value not exceeding the constant current value allowed by the secondary battery, and The output of the current detector 56 is the AC adapter 5
The current excluding the amount consumed by the information processing device 52 within the allowable range of 1 is supplied to the charging of the secondary battery.

[0006]

In this charging method, a small-capacity AC adapter is used in order to allocate a maximum amount of current excluding the current consumed according to the operation state of the information processing apparatus to the charging of the secondary battery. Although it has the advantage of being able to charge in a short time, it is necessary to measure the output current of the AC adapter so as not to exceed the capacity of the AC adapter and the charging current so as not to exceed the charging current of the secondary battery. There is a need for a current detection unit, and there is a need for charging control of a secondary battery that does not increase the number of components for such current detection and that causes less power loss due to a voltage drop in the current detection unit.

SUMMARY OF THE INVENTION It is an object of the present invention to realize an information processing apparatus having a charging function of a secondary battery with a simple circuit configuration and a small power loss by a current detection unit.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a method for controlling the output of an AC adapter when the maximum current consumption of an information processing device is lower than the allowable charging current of a secondary battery. The power is supplied within the range of the maximum allowable charging current (hereinafter abbreviated as allowable charging current), and the current is proportionally divided between the information processing device and the secondary battery. The terminal voltage of the secondary battery is measured, and when the battery is almost fully charged, the operation is switched to the constant voltage operation to control the battery from being overcharged.

When the maximum current consumption of the information processing apparatus is higher than the allowable charging current of the secondary battery, the information processing apparatus including the operation state of the information processing apparatus is in the suspended state or the stopped state, and the current consumption is very small. In this case, the same current as in the above control is supplied.
Charging control is performed by changing the output current of the adapter to a value higher than the allowable charging current within a range not exceeding a value obtained by adding the allowable charging current value of the secondary battery and the minimum current consumption of the information processing device.

As a result, the charge control can be performed by the one-stage current detection unit, and an information processing apparatus having a simple circuit configuration and a function of charging a secondary battery with small power loss can be realized.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides an information processing apparatus, a secondary battery, an AC adapter for charging the secondary battery and supplying power to the information processing apparatus, A voltage detection unit that measures a terminal voltage of the secondary battery,
A current detector for measuring a current supplied by the AC adapter; a constant voltage / constant current controller for controlling the output of the AC adapter to be driven at a constant current or a constant voltage; the current detector and the voltage detector And a control unit that controls the constant-voltage / constant-current control unit in response to the detected value, wherein the charging of the secondary battery is a constant-voltage / constant-current charging, and the current value of the constant current during charging is the information processing device. Is larger than the maximum load current of the secondary battery, the voltage detector controls the control unit to drive the constant voltage / constant current control unit at a constant current while the charge state of the secondary battery is empty or in the middle of charging, and the voltage An information processing unit having a function of charging a secondary battery, wherein the control unit controls the constant-voltage / constant-current control unit to drive at a constant voltage when the detection unit detects that the battery is approaching full charge. Device Has the effect that the information processing apparatus having a charging function of the small secondary battery power loss in the charge control can and become simple circuit configuration by the current detection portion of the first stage can be realized.

According to a second aspect of the present invention, there is provided an information processing apparatus, a secondary battery, an AC adapter for charging the secondary battery and supplying power to the information processing apparatus, and the secondary battery. A voltage detector for measuring a terminal voltage of the AC adapter; a current detector for measuring a current supplied by the AC adapter;
A constant-voltage / constant-current control unit that controls the output of the adapter to be driven with a constant current or a constant voltage; and a constant voltage that receives a value detected by the current detection unit and the voltage detection unit and a state of the information processing apparatus. A control unit that controls a constant current control unit, wherein the charging of the secondary battery is a constant voltage constant current charging, and the control unit is configured such that the voltage detection unit determines that the charging state of the secondary battery is empty or in the middle of charging. The constant voltage / constant current control unit is controlled to be driven at a constant current, and when the information processing device is in an operating state, the constant voltage / constant current control unit has a first current value, and the information processing device is in a non-operating state. Alternatively, in the standby state, the constant-voltage / constant-current control unit controls the current to be a second current value smaller than the first current value, and the control is performed when the voltage detection unit detects that the battery is approaching full charge. Section is the constant current An information processing device having a secondary battery charging function, characterized in that the constant current control unit is controlled to be driven at a constant voltage.The maximum current consumption of the information processing device is larger than the allowable charging current of the secondary battery. Even when large,
The single-stage current detection unit enables charging control, and has an effect that an information processing device having a function of charging a secondary battery with low power loss can be realized with a simple circuit configuration.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a block diagram including information processing apparatus and charging control of a secondary battery according to the present invention. An AC adapter 11 supplies power required for operation of the information processing device 12 and power required for charging the secondary battery 13. Reference numeral 14 denotes a backflow prevention diode, which prevents an abnormal current from flowing into the secondary battery even if a failure occurs. 16
Is a current detection unit for detecting a current supplied by the AC adapter, and 18 is a voltage detection unit for detecting a terminal voltage of the secondary battery. Based on the output of the current detection unit 16 and the output of the voltage detection unit 18, the control unit 17 checks the state of charge of the secondary battery 13
The constant voltage / current control unit 15 is controlled so that the output of the C adapter 11 operates at a constant current or a constant voltage.

In general, a secondary battery is charged by constant voltage / current charging control. In this method, the remaining amount of the secondary battery is checked by the terminal voltage of the battery, and when the battery is empty to less than full charge, the battery is charged by applying a charging current equal to or less than the allowable charging current value A1. Thereafter, when charging proceeds and the terminal voltage rises, it is detected that full charge is approaching, and thereafter constant voltage charging is performed to prevent overcharging. If a current exceeding the allowable charging current is applied during constant-current charging, a stress is applied to the battery. However, as long as the battery is charged with a current lower than that, only the charging time is lengthened and there is no quality effect.

FIG. 2 shows constant voltage / constant current control in an information processing apparatus having a charging function for a secondary battery having the above configuration. This is when the maximum current consumption of the information processing device 12 is smaller than the allowable charging current of the secondary battery 13, and when the charging amount is smaller than the full charge, the output of the AC adapter 11 is set to the value of the allowable charging current. And outputs the output to the information processing device 12.
And the charge of the rechargeable battery is proportionally divided, and when the rechargeable battery approaches the full charge, the voltage is switched to a constant voltage thereafter to prevent the rechargeable battery from being overcharged.

From the empty state to the point Ta, the control section 17 receives the output of the current detection section 16 and controls the constant voltage / constant current control section 15 so that the output of the AC adapter 11 becomes a constant current. To control. During this time, the current consumed by the information processing device 12 fluctuates as indicated by the load current in the figure, so that the secondary battery 13 is charged in an area above the load current.

As the charging proceeds, the terminal voltage of the secondary battery 13 rises, and when the output of the voltage detector 18 reaches a specified value, it is determined that the full charge is approaching (at the point of time Ta). Switch to voltage operation. Thereafter, similarly, the current consumption and the charging current of the information processing device 12 are supplied from the AC adapter 11.

Strictly speaking, the time up to Ta is affected by the magnitude of the load current, and as the load current increases, the current used for charging decreases and the time increases, but the same behavior is exhibited except for the absolute time. It is shown on the same time axis as the case of no load described in FIG.

The voltage supplied to the information processing device 12 is affected by the degree of charge of the secondary battery. However, since the inside is composed of components operating at various voltages, the power input is used as it is. Instead, a voltage suitable for each component is generated by a DC-DC converter.
For this reason, even if the input voltage fluctuates somewhat, the current consumption only fluctuates in accordance therewith, and the operation is not affected.

By providing a temperature detecting section inside or near the battery and inputting the output of the temperature detecting section to the control section for control, it is possible to perform power supply control in consideration of the temperature characteristics of the battery. Become.

Further, by mounting the constant-voltage / constant-current control unit 15, the current detection unit 16, the voltage detection unit 18, and the control unit 17 in the AC adapter 11, a power supply control circuit on the information processing apparatus side is provided. Is simplified and the information processing apparatus can be downsized.

(Embodiment 2) FIG. 3 is a block diagram including charging control of an information processing apparatus and a secondary battery according to the present invention.
This is a case where charging control is also performed based on information on load fluctuation. An AC adapter 31 supplies power required for operation of the information processing device 32 and power required for charging the secondary battery 33. Reference numeral 34 denotes a backflow prevention diode which prevents an abnormal current from flowing into the secondary battery even if a failure or the like occurs. 36
Reference numeral denotes a current detection unit that detects a current supplied by the AC adapter, and reference numeral 38 denotes a voltage detection unit that detects a terminal voltage of the secondary battery. Based on the output of the current detection unit 36, the output of the voltage detection unit 38, and the state of the information processing device 32, the control unit 37 checks the state of charge of the secondary battery 33 and operates the output of the AC adapter 31 in a constant current operation or a constant voltage operation. The constant voltage / current control unit 35 is controlled to perform the control.

FIG. 4 shows a constant voltage / constant current control in the information processing apparatus having the function of charging the secondary battery having the above configuration. This is because, when the maximum current consumption during the operation of the information processing device 32 is larger than the allowable charging current of the secondary battery 33 and the current consumption becomes smaller than the allowable charging current when the operation state is, for example, suspended or stopped, the current consumption is lower than the full charging. When the amount of charge is small and the information processing device 32 is operating, control is performed so that the current value A2 exceeds the maximum current consumption of the information processing device 32.
When the information processing device 32 is suspended or stopped (Tb
At that time, the information is transmitted to the control unit 37, and the output of the constant-voltage / constant-current control unit 35 is used as the value A of the allowable charging current of the secondary battery 33.
Control to lower to 1. This prevents an excessive current from being applied to the secondary battery 33. Information processing device 3 again
The current value is increased to A2 at the point of time when T2 starts (Tc point).

As the charging progresses, the terminal voltage of the secondary battery 33 rises, and when the output of the voltage detector 38 reaches a specified value, it is determined that the full charge is approaching (at time Td). Switch to voltage operation.

[0026]

As described above, according to the present invention, it is not necessary to individually measure the charging current of the secondary battery and control the charging, so that the output of the AC adapter can be effectively utilized and the information processing device side can be used. The charge control circuit can be omitted,
An advantageous effect that a small and highly portable information processing device can be realized is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a charging circuit including an information processing device and a secondary battery according to an embodiment of the present invention.

FIG. 2 is a diagram showing changes in the amount of charge and current / voltage in constant voltage / constant current control in one embodiment of the present invention.

FIG. 3 is a block diagram of a charging circuit including an information processing device and a secondary battery according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a change in a charge amount and a current / voltage of a constant voltage / constant current control in a second embodiment of the present invention.

FIG. 5 is a block diagram of a charging circuit including a conventional information processing device and a secondary battery.

FIG. 6 is a diagram showing a change in a charge amount and a current / voltage of a constant voltage / constant current control in a conventional example.

[Explanation of symbols]

 11, 31, 51 AC adapter 12, 32, 52 Information processing device 13, 33, 53 Secondary battery 14, 34, 54 Backflow prevention diode 15, 35, 55 Constant voltage constant current control unit 16, 36, 56 Current detection unit 17, 37, 57 control unit 18, 38, 58 voltage detection unit 59 charging current detection unit

Claims (2)

[Claims] A rechargeable battery, an AC adapter for charging the rechargeable battery and supplying power to the information processing device, a voltage detection unit for measuring a terminal voltage of the rechargeable battery, and the AC adapter. A current detector for measuring a current to be supplied;
A constant voltage / constant current control unit for controlling the output of the C adapter to be driven with a constant current or a constant voltage; and controlling the constant voltage / constant current control unit in response to the values detected by the current detection unit and the voltage detection unit. The secondary battery is charged at a constant voltage and constant current, and the current value of the constant current at the time of charging is larger than the maximum load current of the information processing device. The control unit controls the constant-voltage / constant-current control unit to perform constant-current driving when the battery is empty or in the middle of charging, and performs the control when the voltage detection unit detects that the battery is approaching full charge. An information processing apparatus having a function of charging a secondary battery, wherein the information processing unit controls the constant-voltage / constant-current control unit to perform constant-voltage driving. 2. A secondary battery, an AC adapter for charging the secondary battery and supplying power to the information processing device, a voltage detector for measuring a terminal voltage of the secondary battery, and the AC adapter. A current detector for measuring a current to be supplied;
A constant-voltage / constant-current control unit for controlling the output of the C adapter to be driven with a constant current or a constant voltage; and a constant-current control unit that receives the values detected by the current detection unit and the voltage detection unit and the state of the information processing device. A control unit that controls a voltage / constant current control unit, wherein the charging of the secondary battery is a constant voltage / constant current charging, and the voltage detection unit is configured to control the control unit when the charging state of the secondary battery is empty or in the middle of charging. Controls the constant voltage / constant current control unit to perform constant current driving, and when the information processing device is in the operating state, the constant voltage / constant current control unit has the first current value, and the information processing device does not operate. In the state or the standby state, the constant voltage / constant current control unit controls the current value to be a second current value smaller than the first current value, and when the voltage detection unit detects that the battery is approaching full charge, The control unit An information processing apparatus having a function of charging a secondary battery, wherein the information processing apparatus controls the voltage / current control unit to be driven at a constant voltage.