JPH04236134A - Charge/discharge device - Google Patents

Abstract

PURPOSE:To realize a charging/discharging device which does not require any special discharge circuit using a discharge resistance nor fan, etc., for heat radiation and can be reduced in size. CONSTITUTION:When the voltage of a battery 2 drops below a prescribed value, a main switch 15 is turned on in accordance with an instruction from an auxiliary CPU 1. Then the CPU 1 requests a forcible discharge and a CPU 7 is actuated and performs the forcible discharge by repeating pseudoexecution of read/ write against the vacant area of a main memory 10. After the forcible discharge is completed, the main switch 15 is turned off and the auxiliary CPU 1 starts the charging of the battery 2 by resetting a counter 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging/discharging device for charging and discharging batteries used as a power source for electronic devices such as desktop-type and book-type small computers.

0002

2. Description of the Related Art In recent years, small computers called desktop type or book type computers have become increasingly important due to their ability to be easily carried when moving, and there is a demand for further miniaturization. Such small computers use rechargeable storage batteries, such as nickel-cadmium batteries, as a means of supplying power.

[0003] A conventional charging/discharging device will be explained below. Once a storage battery has been charged, it is desirable to discharge it 100% before charging it again. However, in general, as shown in FIG. 3, depending on the user's usage conditions, the next charge is often performed before the battery is fully discharged. If you repeat this process, the unused parts of the battery will become inactivated, and even if you try to use the battery 100% after charging, only a part of the battery capacity will still be used, as shown at point A in Figures 3 and 4. Despite this, the battery voltage drops quickly and requires recharging. This phenomenon is called the battery memory effect. To prevent this memory effect,
Conventionally, as shown in FIG. 5, a method has been adopted in which a discharge circuit using a discharge resistor is provided to once forcibly discharge the storage battery by 100%, and then the battery is charged by a charging circuit.

0004

[Problems to be Solved by the Invention] However, in conventional charging/discharging devices, the discharge resistor has a large shape in order to perform forced discharge, and also generates a large amount of heat, so the discharge circuit becomes large and heat dissipation is required. It is necessary to provide a fan or the like for this purpose, which poses a problem in that it is a major hindrance to the miniaturization of electronic equipment using this. An object of the present invention is to provide a charging/discharging device that eliminates such problems.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention is configured to have a means for forcibly discharging the battery by using at least a part of the main body as a load before charging the battery. .

[0006]

[Operation] According to the present invention, by using the above-mentioned means, forced discharge is performed using the main unit as a load before charging is performed.

[0007]

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

FIG. 1 is a block diagram of a charging/discharging device according to an embodiment of the present invention, in which 1 is an auxiliary central processing unit (hereinafter referred to as CPU) that manages charging, 2 is a storage battery,
3 is a charging circuit that charges the storage battery 2 under the control of the auxiliary CPU, 4 is a DC power source that supplies DC power to the auxiliary CPU 1 and the charging circuit 3, and 5 is a memory that stores the number of charging times counted by the auxiliary CPU 1. Counter, 6 is auxiliary CP
A charging start request unit requests U1 to start charging, 7 is a main CPU that controls the main body of the electronic device, 8 is an LED display unit, 9 is an LCD display unit, and 10 is a main memory. 15
is a switch for turning ON/OFF the supply of power to the main CPU 7, and is controlled by the auxiliary CPU 1. 16
is connected to the S2 side when the DC power supply 4 is connected, and to the S1 side otherwise.

The operation of the charging/discharging device of this embodiment constructed as described above will be explained below using the flowchart shown in FIG.

First, in S21, when a request is made from the charging start requesting unit 6 to the auxiliary CPU 1 to start charging, the auxiliary CPU 1 checks the counter 5 in S22 and determines that the value is a predetermined value (denoted as N). ) is reached, and if it has been reached, the process moves to S23, and if it has not been reached, the process moves to S30.

If the value of the counter 5 has not reached N, the auxiliary CPU 1 instructs the charging circuit 3 to start charging in S30, and charging of the storage battery 2 is started. When charging is started, the auxiliary CPU 1 detects the terminal voltage on the storage battery side of the charging circuit 3 in S31, and when the end of charging is detected based on the terminal voltage, the charging circuit 3 is Stop charging the storage battery 2. When charging is completed, the auxiliary CPU 1 counts up the counter 5 by 1, and the charging process ends. Here, the count-up of the counter 5 does not have to be based on the detection of the battery voltage; for example, when a timer is activated at the start of charging and the timer counts a predetermined time,
Any means may be used as long as the number of times of charging can be counted, such as counting up the counter 5.

When the value of the counter 5 has reached N, first, in S23, the main switch 15 is turned on by an instruction from the auxiliary CPU 1. Next, when the auxiliary CPU 1 requests forced discharge in S24, the main CPU 7 is activated in S24, and the main memory 1 is activated in S25.
Forced discharge is started by repeating pseudo reading/writing to the empty area of 0. While the forced discharge is being performed, the auxiliary CPU 1 detects the terminal voltage on the storage battery side of the charging circuit in S26, and when it becomes lower than a predetermined voltage, it is determined that the discharge has been completed, and the auxiliary CPU 1 detects the terminal voltage on the storage battery side of the charging circuit.
After the main CPU 7 is reset in S27 according to the instruction, the main switch 15 is turned off in S28. When the forced discharge is completed and the main switch is turned off, the auxiliary CPU 1 resets the counter 5 in S29, and thereafter the storage battery 2 is charged by the processes from S30 described above.

As described above, in this embodiment, forced discharge is performed by driving a part of the device that cannot be visually recognized by the user, so there is no need to provide a special discharge circuit using a discharge resistor, and the charging The discharge device itself can be made smaller, and since there is no need to provide a heat dissipation means such as a fan, it can greatly contribute to the miniaturization of electronic equipment.

Furthermore, in this embodiment, the number of times the battery is charged is counted and forced discharge is performed every predetermined number of times. can prevent memory effects.

In this embodiment, the forced discharge of the battery is performed by driving the main CPU and pseudo reading/writing to the main memory. It is sufficient if the operation of the motor or the like is not easily recognized by the user.

[0016]

[Effects of the Invention] Since the present invention performs forced discharge of a storage battery using a part of the main body of the device as a load, there is no need to provide a special discharge circuit using a discharge resistor, and the charging/discharging device itself can be miniaturized. Since there is no need to provide a heat dissipation means such as a fan, it can greatly contribute to the miniaturization of electronic devices.

[Brief explanation of the drawing]

FIG. 1: Block diagram of one embodiment of the present invention

FIG. 2 is a flowchart showing the operation of an embodiment of the present invention.

[Figure 3] Explanatory diagram showing the battery capacity when charging is repeated with insufficient discharge

[Figure 4] Voltage characteristic diagram showing voltage characteristics when memory effect occurs in a battery

[Figure 5] Block diagram of a conventional charging/discharging device

[Explanation of symbols]

1 Auxiliary CPU 2 Storage battery 3 Charging circuit 4 DC power supply 5 Counter 6 Charging start request section 7 Main CPU 8 LED display section 9 LCD display section 10 Main memory

Claims (4)

[Claims] 1. A charging/discharging device characterized in that, before charging a rechargeable battery, the battery is forcibly discharged by using at least a portion of the main body as a load. 2. The charging/discharging device according to claim 1, wherein the load is one whose operation is not recognized from the outside. 3. A charging/discharging device that counts the number of times the battery has been charged and forcibly discharges the battery every predetermined number of times before charging. 4. The charging/discharging device according to claim 2, wherein the load is repeated read/write operations on empty space in the memory of the main body.