JPH04244740A - Charger - Google Patents

Abstract

PURPOSE:To prevent no charge current to a battery when the residual capacity of the battery is low. CONSTITUTION:A battery pack A is connected to a separate charger B, and a battery 1 is charged. The pack A has a control circuit 3. The charger B has a transistor Q2 for opening/closing a charge route of the battery 1. The circuit 3 senses the residual capacity of the battery 1, and stops charging of the battery B if the capacity reaches a predetermined value. A switch circuit 6 is provided between the output terminal O1 for controlling charge of the circuit 3 and the control terminal C of the charger B. The circuit 6 receives a power from the charger B to operate except the case in which the battery 1 fully charged, and turns On the transistor Q2 of the charger B. The circuit 6 controls the battery 1 to a charging state by the charger B except the case in which the battery 1 is fully charged. Accordingly, the battery is always charged even if the residual capacity of the battery is low.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention consists of a battery pack installed in a portable device, etc., and a charger that is separate from the battery pack and charges the battery when the battery pack is connected. The present invention relates to a charging device.

0002

2. Description of the Related Art In portable devices such as video cameras and mobile phones, the battery pack that supplies power to the main body of the device is detachable, and when the battery is to be charged, the battery pack is removed from the main body of the device. Some devices charge using a separately provided charger.

[0003]In this type of device, for example, as disclosed in Japanese Patent Application No. 2-204691, in order to simplify the circuit configuration of the charger and reduce costs, the remaining capacity of the battery is detected on the battery pack side. Some devices include a remaining capacity detecting means for detecting the remaining capacity, and a charging control means for controlling the operation of the charger according to the remaining capacity detected by the remaining capacity detecting means.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned charging device that controls the charger from the battery pack, the remaining capacity detection means and charging control means operate using the battery as a power source, so the remaining capacity of the battery is low. When the remaining capacity detection means and the charging control means become unstable, the battery may not be able to be charged by the charger, and when the battery capacity is completely exhausted, the remaining capacity detection means and the charging control means may become unstable. The control means becomes inoperative and the battery cannot be charged.

The present invention has been made in view of the above points, and its object is to provide a charging device that can reliably charge a battery even when the remaining capacity of the battery is low. It is in.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a remaining capacity detecting means for detecting the remaining capacity of a battery, and a charger according to the remaining capacity detected by the remaining capacity detecting means. A charge control means for controlling the state of charge of the battery is provided on the battery pack side, and a switch element inserted in series in the charge path of the battery and controlled on and off by the output of the charge control means is provided on the charger. The output of the control means is configured to be in an output state that turns on the switch element except when the battery is fully charged.

[0007]In addition, in order to correct the remaining capacity detection error due to the remaining capacity of the battery when the battery is charged for the first time, a non-volatile storage means for storing whether the battery was previously fully charged and a The battery pack is provided with a full charge detection means for detecting that it is fully charged, and until the battery is fully charged for the first time, the charging control means does not rely on the remaining capacity detection output from the remaining capacity detection means. It is preferable to control the battery charging state of the charger according to the output of the battery charger.

[0008] Furthermore, when the above-mentioned charger rapidly charges the battery, the charging control means turns on and off the switch element to charge the battery with a trickle current, thereby making it possible to carry out supplementary charging after the completion of charging the battery. Can be done.

[0009]

[Operation] As described above, the present invention is configured such that the output of the charging control means is in an output state that turns on the switch element except when the battery is fully charged, so that the battery is not fully charged. When the battery pack is connected, the charger always supplies charging current to the battery pack, so that the battery can be reliably charged even when the remaining capacity of the battery is low.

0010

[Example] A charging device as an example of the present invention is shown in FIG.
As shown in the figure, there is a battery pack A that is installed in a portable device and is removable from the device body, and a battery pack A that is separate from the battery pack A and charges the battery 1 when the battery pack A is connected. It consists of a charger B that performs

Charger B includes a transformer T to which commercial power AC is supplied to the primary winding side, and a transistor Q2 as a switching element connected in series to the secondary winding of the transformer T.
, a diode D1 for backflow prevention, and resistors R3, R
4, both ends of the series circuit of the transistor Q2, the secondary winding of the transformer T, and the diode D1 serve as charging terminals + and - for charging the battery 1, and are connected to the base of the transistor Q2 via a resistor R3. terminal C
is the control terminal.

[0012] The charging terminal + of charger B is on the battery pack A side.
, -, respectively, and an output terminal connected to a control terminal C, and the battery 1 is connected between the input terminals via a resistor R0. A constant voltage circuit 2 is connected to both ends of the battery 1, and this constant voltage circuit 2 (for example, a 3-terminal regulator) creates a constant voltage from the voltage applied to both ends of the battery 1 and applies it to each part described later. Supply power. This battery pack A includes a control circuit that constitutes a remaining capacity detection means that detects charging current and discharging current from the voltage across a resistor R0 connected in series with the battery 1, and calculates the remaining capacity of the battery 1. 3, and this control circuit 3 displays the determined remaining capacity on a display section 4 provided in this battery pack A. Further, the remaining capacity calculated by the control circuit 3 is stored in a nonvolatile memory 5 (eg, EEPROM). Furthermore, this control circuit 3 includes a battery 1.
It is equipped with a judgment means for judging the operation control state of the charger B from the remaining capacity of the charger B, and the charger B is charged according to the output O1 of the control circuit 3 which switches between the open state and the active low state according to the judgment result of this judgment means. Transistor Q1 and resistor R1 that switch control terminal C of device B between high and low
, R2, and the determination means and the switch circuit 6 constitute charging control means.

The operation of the above-described configuration will be explained. Now, in order to charge battery 1, which has a certain amount of remaining capacity, battery pack A, which has been removed from the main body of the device, is connected to charger B.
Suppose you connect to In this case, since the battery 1 is not fully charged, the output O1 of the control circuit 3 is in an open state. In this case, the AC power supply AC is connected via resistors R1 to R4, transistor Q1, and diode D1.
The base current flows into the transistor Q1, turning on the transistor Q1, and pulling the control terminal C of the charger B to a low level.Therefore, the base current flows through the transistor Q2, turning it on, and connecting the AC power source AC to the diode D1. The rectified DC current is supplied to the battery 1, and the battery 1 is charged.

In the case of this embodiment, even if battery pack A is connected to charger B in a state where battery 1 is completely discharged, charger B will be in the state of charging battery 1 in the same way. In other words, when battery pack A is connected to charger B with battery 1 running out of remaining capacity, control circuit 3
Since no power is supplied to the control circuit 3, the control circuit 3 is essentially disconnected from the switch circuit 6. Therefore, the resistors R1 to R4,
A base current flows from the AC power supply AC to the transistor Q1 through the transistor Q1 and the diode D1, and the transistor Q1 is turned on. Therefore, charger B
A charging current is supplied from the battery 1 to the battery 1. and,
In this case, the constant voltage circuit 2 creates a power source from the voltage applied between the input terminals from the charger B and supplies it to each part, so the control circuit 3 etc. start operating normally. However, in this case as well, the output O1 of the control circuit 3 is in the open state, so the above state continues as it is. In this way, in this embodiment, when the battery pack A is connected to the charger B while the battery 1 is not fully charged, the switch circuit 6 always turns on the transistor Q2 to start charging from the charger B. Therefore, there is no problem that the battery 1 cannot be charged normally when the remaining capacity of the battery 1 is low as in the conventional case.

In this manner, while the battery 1 is being charged, the control circuit 3 detects the charging current from the voltage across the resistor R0, and adds it to the remaining capacity stored in the memory 5 every unit time. Find the current remaining capacity. Memory 5 at this time
The contents will be updated sequentially. When the remaining capacity reaches a specified value, the output O1 of the control circuit 3 becomes low, the transistor Q1 is turned off, and the control terminal C becomes high level. Therefore, at this time, transistor Q2 is turned off and charging of battery 1 is stopped.

When the fully charged battery pack A is attached to the main body of the apparatus, the input terminal becomes a power supply terminal, and power is supplied to the main body of the apparatus. Assuming that the device is now in use, the current remaining capacity is determined by detecting the discharge current of the battery 1 from the voltage across the resistor R0 and subtracting it from the remaining capacity. By determining the current remaining capacity of the battery 1 in this way and displaying it on the display unit 4, the user can determine the charging time and the battery pack B based on the remaining capacity of the battery 1.
You can accurately judge when to replace the.

[0017] In addition to the circuit configuration of battery pack A described above, it is conceivable to adopt a configuration that allows charging from charger B when control terminal C is at a high level. In this case, even when battery pack A is not connected, charger B is in a charging state, and voltage is always applied to charging terminals + and -, which is unfavorable from a safety point of view.

By the way, in this type of charging device that performs charging control according to the remaining capacity, it is necessary to initialize the remaining capacity when charging the battery 1 for the first time. That is, when the battery 1 is charged for the first time, the remaining capacity of the battery is not constant, so if it is used as is, an error will occur depending on the remaining capacity of the battery 1. To solve this problem, when charging the battery for the first time, either fully charge the battery with a proper charger that will not overcharge the battery, or use a trickle current that will not cause any problem even if the battery is overcharged. One possible method is to charge the battery 1 for about a day and have the remaining capacity detection means recognize that the battery 1 is 100% charged, but this method requires unnecessary effort and cost.

Therefore, in this embodiment, data for determining whether or not the battery 1 is fully charged is previously written in the memory 5, and until the battery 1 is once fully charged, the data is stored according to the remaining capacity as described above. The operation of battery charger B is not controlled, and battery 1 is
Charge control of the battery 1 is performed using a commonly used charge detection method for detecting full charge of the battery 1. That is, in this embodiment, as shown in FIG. 1, a temperature sensor 7 such as a thermistor placed close to the battery 1 is provided, and a function to detect the battery voltage from the voltage applied to the input terminal I3 is controlled. The circuit 3 is provided with the control circuit 3 so that the control circuit 3 can determine whether the battery 1 is fully charged or not based on battery voltage information and battery temperature information. Note that the control circuit 3 is configured to detect charging/discharging current and battery temperature through input terminals I1 and I2.

That is, in this embodiment, the user is instructed to fully charge the battery 1 when charging it for the first time. Here, whether or not the battery 1 is fully charged is detected from -ΔV due to a decrease in battery voltage from its peak value and an increase in battery temperature. Note that it is not necessarily necessary to detect both the battery voltage and the battery temperature as in this embodiment, and the fully charged state may be detected using only one of them. Once fully charged, data indicating that the battery is fully charged is written to the memory 5, and once the battery is fully charged in this way, the charging of the battery 1 is controlled based on the remaining capacity as described above. Make sure to do the following. In this way, errors in remaining capacity can be corrected without unnecessary effort or cost. Capacitance detection accuracy can be improved. At this time, since the display unit 4 displays that the battery 1 is fully charged, the user can reliably know that the battery 1 is fully charged.

By the way, in the above case, when battery 1 was fully charged, charging of battery 1 was completely stopped;
When rapidly charging the battery 1, it is preferable to perform supplementary charging, that is, charging with a trickle current with a low current value, after charging of the battery 1 is completed, to completely charge the battery to its rated capacity. Therefore, when the battery 1 is rapidly charged, after the charging is completed, the transistor Q1 is turned on by the control circuit 3.
By turning off the transistor Q2, the transistor Q2 can be turned on and off to perform supplementary charging. Note that even if the battery 1 is charged with a pulsed current in this manner, there is no problem because the battery 1 is charged with an average current. Further, the value of the trickle current can be decreased gradually (stepwise in the case of the embodiment) as shown in FIG. 2(a). In this case, the on/off ratio may be varied to vary the high/low ratio of the control terminal C, as shown in second (b).

[0022]

As described above, the present invention includes a remaining capacity detecting means for detecting the remaining capacity of a battery, and a charger for controlling the battery charging state of a charger according to the remaining capacity detected by the remaining capacity detecting means. A control means is provided on the battery pack side, and it is inserted in series in the charging path of the battery and turned on and off by the output of the charging control means.
The charger is provided with a switch element that is controlled to be turned off, and the output of the charge control means is configured to turn on the switch element except when the battery is fully charged. When a battery pack that is not in the current state is connected, the charger always enters a state in which charging current is supplied to the battery pack, so that the battery can be reliably charged even when the remaining capacity of the battery is low.

[0023] Furthermore, the battery pack is provided with a non-volatile storage means for storing whether or not the battery was previously fully charged, and a full charge detection means for detecting that the battery is fully charged, so that the battery is fully charged for the first time. Until the battery is charged, the charging control means controls the battery charging state of the charger according to the output of the full charge detection means, without depending on the remaining capacity detection output of the remaining capacity detection means, and then the battery is charged only when the battery is charged. In this case, by fully charging the battery, it is possible to correct the error in detecting the remaining capacity due to the remaining capacity of the battery, and it is possible to improve the accuracy in detecting the remaining capacity.

Furthermore, when the charger quickly charges the battery, the charge control means turns on and off the switch element to charge the battery with trickle current during supplementary charging after the battery is fully charged. When rapidly charging a battery, supplementary charging can be performed after charging of the battery is completed.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a battery pack and a charging device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing supplementary charging after charging is completed when rapid charging is performed in the same as above.

[Explanation of symbols]

A Battery pack B Charger 1 Battery 3 Control circuit 5. Memory 6 Switch circuit 7 Thermistor Q2 Transistor R0 resistance

Claims (3)

[Claims] 1. A charging device comprising a battery pack installed in a portable device, etc., and a charger that is separate from the battery pack and charges the battery when the battery pack is connected, Remaining capacity detection means for detecting the remaining capacity of the battery;
A charging control means for controlling the battery charging state of the charger according to the remaining capacity detected by the remaining capacity detecting means is provided on the battery pack side, and the charging control means is inserted in series in the charging path of the battery and is connected to the output of the charging control means. The charger is provided with a switch element that is controlled to turn on and off, and is configured such that the output of the charging control means is in an output state in which the switch element is turned on except when the battery is fully charged. charging device. Claim 2: A battery pack is provided with a non-volatile storage means for storing whether or not the battery was previously fully charged, and a full charge detection means for detecting that the battery is fully charged, and the battery is fully charged for the first time. A charging device characterized in that, until charging, the charging control means controls the battery charging state of the charger according to the output of the full charge detection means, without depending on the remaining capacity detection output of the remaining capacity detection means. . 3. In the case where the charger rapidly charges the battery, the charging control means turns on and off a switch element to charge the battery with a trickle current during supplementary charging after charging of the battery is completed. Charging device.