JP3457681B2 - Charging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a battery pack mounted on a portable device and the like, and a charger for charging the battery when the battery pack is connected separately from the battery pack. The present invention relates to a charging device.

[0002]

2. Description of the Related Art In a portable device such as a video camera or a mobile phone, a battery pack for supplying power to the device body is detachable, and when the battery is charged, the battery pack is removed from the device body. There is one that is charged by a charger provided separately.

By the way, in this type of device, the remaining capacity of the battery is detected on the battery pack side in order to simplify the circuit structure of the charger and reduce the cost, as in Japanese Patent Application No. 2-204691. There is provided a remaining capacity detecting means and a charging control means for controlling the operation on the charger side according to the remaining capacity detected by the remaining capacity detecting means.

[0004]

However, in the above-mentioned charging device for controlling the charger from the battery pack, the remaining capacity of the battery is small because the remaining capacity detection means and the charging control means operate with the battery as a power source. In this case, the operation of the remaining capacity detection means and charge control means may become unstable, and the battery may not be charged by the charger.If the battery capacity is completely exhausted, the remaining capacity detection means and charging The control means becomes inoperative and the battery cannot be charged.

The present invention has been made in view of the above points, and an object of the present invention is to provide a charging device capable of reliably charging a battery even when the remaining capacity of the battery is small. It is in.

[0006]

According to the present invention, in order to achieve the above object, a remaining capacity detecting means for detecting a remaining capacity of a battery and a charger depending on the remaining capacity detected by the remaining capacity detecting means. And a charge control means for controlling the battery charge state of the battery are provided on the battery pack side to supply power from the battery to the remaining capacity detection means and the charge control means, and are inserted in series in the charge path of the battery , and control terminals are set to high and low. The charging device is provided with a switch element which is turned on / off by the output of the charging control means, and the charging device is operated based on the remaining capacity detected by the remaining capacity detecting means.
Means for judging the motion control state of the
Switch the control terminal of the charger to high or low according to the disconnection result.
The charging control means is configured by such a switch circuit, and the output of the charging control means is in an output state in which the switching element is turned on except when the battery is fully charged.

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, the nonvolatile storage means for storing whether or not the battery has been fully charged before, and the battery The battery pack is provided with a full-charge detecting means for detecting that the battery is fully charged, and until the battery is fully charged for the first time, the charge control means does not depend on the remaining-capacity detection output by the remaining-capacity detecting means, It is preferable to control the battery charge state of the charger in accordance with the output of.

Further, in the case where the charger rapidly charges the battery, if the charging control means turns the switch element on and off to charge the battery with the trickle current, the auxiliary charge is performed after the charging of the battery is completed. You can

[0009]

According to the present invention, the battery is not in the full charge state by configuring the output of the charge control means to be in the output state in which the switch element is turned on except when the battery is in the full charge state as described above. When the battery pack is connected, the charger always supplies the charging current to the battery pack, so that the battery can be surely charged even when the remaining capacity of the battery is small.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A charging device as an embodiment of the present invention is shown in FIG.
As shown in FIG. 2, a battery pack A that is installed in a portable device and is detachable from the device main body, and charging of the battery 1 when the battery pack A is connected separately from the battery pack A And a charger B for performing.

The charger B includes a transformer T, to which a commercial power supply AC is supplied on the primary winding side, and a transistor Q as a switch element connected in series to the secondary winding of the transformer T.
₂ , a backflow prevention diode D ₁ , and resistors R ₃ and R ₄
It consists of a transistor Q ₂ and a transformer T 2.
Both ends of the series circuit of the _secondary winding and the diode D ₁ serve as charging terminals + and − for charging the battery 1, and the terminal C connected to the base of the transistor Q ₂ via the resistor R ₃ serves as a control terminal.

On the side of the battery pack A, the charging terminal of the charger B
Connected to the input terminal and control terminal C, which are connected to + and − respectively
Output terminal, and the battery 1 is between the input terminals
Resistance R ₀Connected via. Both ends of this battery 1
The constant voltage circuit 2 is connected, and the constant voltage circuit 2 (for example,
For example, it is applied to both ends of the battery 1 with a 3 terminal regulator).
Create a constant voltage from the voltage and supply power to each part described later.
It The battery pack A is connected in series with the battery 1.
Resistor R connected to₀Charge voltage and discharge from voltage across
Remaining capacity detector that detects the current and calculates the remaining capacity of battery 1.
A control circuit 3 that constitutes a stage is provided, and this control circuit 3 is required.
The display unit 4 provided on the battery pack A for the remaining capacity
To display. In addition, the remaining volume calculated by the control circuit 3
The amount depends on the non-volatile memory 5 (eg EEPROM).
Remember Further, the control circuit 3 has a battery 1
Judgment means for judging the operation control state of the charger B from the remaining capacity
In addition to the above, according to the judgment result of this judgment means,
Control circuit that switches between a pun state and an active-low state
Output of 3₁In response to this, the control terminal C of the charger B goes high,
Transistor Q switching to low₁And resistance R₁, R₂
Is provided with a switch circuit 6 consisting of
The charge control means is configured with the H circuit 6.

The operation of the above configuration will be described.
It Now, charge the battery 1 that has a certain remaining capacity.
To remove the battery pack A from the main unit,
Suppose you have connected to B. In this case, the battery 1 should be fully charged.
The output O of the control circuit 3 is not₁Is open
It becomes a state. In this case, the resistance R₁~ R_Four, Transistor
Q₁And diode D₁AC power supply AC via
Current is transistor Q ₁Flow to the transistor Q₁
Is turned on and the control terminal C of the charger B is pulled to low level.
Lowered, so transistor Q₂Base current flows through
Is turned on, the AC power supply AC is connected to the diode D₁By
The rectified direct current is supplied to the battery 1 to charge the battery 1.
Done.

In the case of the present embodiment, even if the battery pack A is connected to the charger B while the battery 1 is completely discharged, the charger B is in a state of charging the battery 1 as well. That is, when the battery pack A is connected to the charger B in the state where the remaining capacity of the battery 1 is exhausted, the control circuit 3 is not supplied with power at this time. It is in a state of being disconnected from the switch circuit 6, and therefore, in the same manner as described above, the AC power source A is connected via the resistors R _{1 to} R ₄ , the transistor Q ₁ and the diode D _1.
A base current flows from C to the transistor Q ₁ and the transistor Q ₁ is turned on. Therefore, from charger B to battery 1
The charging current is supplied to. Then, in this case, the constant voltage circuit 2 creates a power source from the voltage applied from the charger B between the input terminals and supplies it to each part, so that the control circuit 3 and the like start operating normally. However, in this case as well, the output O ₁ of the control circuit 3 is in the open state, so the above state is continued. As described above, 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 Q ₂ to start charging from the charger B. Since the configuration is adopted, there is no problem that the battery 1 cannot be normally charged when the remaining capacity of the battery 1 is small as in the conventional case.

In this way, while the battery 1 is being charged, the control circuit 3 detects the charging current from the voltage across the resistor R ₀ and adds it to the remaining capacity stored in the memory 5 every unit time. Then, the current remaining capacity is calculated. The contents of the memory 5 at this time are also sequentially updated. Then, when the remaining capacity reaches a prescribed value, the output O ₁ of the control circuit 3 becomes low, the transistor Q ₁ is turned off, and the control terminal C becomes high level. Therefore, at this time, the transistor Q ₂ is turned off and the charging of the battery 1 is stopped.

When the fully charged battery pack A is attached to the main body of the apparatus, the input terminal serves as a power supply terminal, and power is supplied to the main body of the apparatus. Assuming that the device is used, the current remaining capacity is obtained by detecting the discharge current of the battery 1 from the voltage across the resistor R _{0 at} this time and subtracting it from the remaining capacity. In this way, the present remaining capacity of the battery 1 is obtained and displayed on the display unit 4,
The user can accurately determine the charging time and the replacement time of the battery pack B from the remaining capacity of the battery 1.

In addition to the circuit configuration of the battery pack A described above, it is conceivable that the charger B can be charged when the control terminal C is at a high level. In addition, even when the battery pack A is not connected, the charger B is in a chargeable state and the voltage is constantly applied to the charging terminals + and −, which is not preferable in terms of safety.

By the way, in a charging device which controls charging according to this kind of remaining capacity, it is necessary to initialize the remaining capacity when the battery 1 is charged 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, and if used as it is, an error corresponding to the remaining capacity of the battery 1 occurs. As a method to solve this, at the time of the first charging, fully charge the battery with an appropriate charger that does not overcharge the battery 1, or use a trickle current that causes no problem even if overcharged. A method is conceivable in which the battery 1 is charged on a daily basis and the remaining capacity detecting means recognizes that the battery 1 is 100% charged, but this has a problem of needless labor and cost.

Therefore, in this embodiment, data for determining whether or not the battery 1 has been fully charged before is written in the memory 5, and until the battery 1 is once fully charged, the above-described remaining capacity is used. The operation of the charger B is not controlled, and the battery 1
The charge control of the battery 1 is performed using a charge detection method which is generally used to detect the full charge of the battery 1. That is, in the present embodiment, as shown in FIG. 1, a temperature sensor 7 such as a thermistor arranged close to the battery 1 is provided, and a battery voltage is detected from the voltage applied to the input terminal I _3. The control circuit 3 is provided so that the control circuit 3 can determine whether the battery 1 is fully charged based on the battery voltage information and the battery temperature information. The control circuit 3 detects the charging / discharging current and the battery temperature at the input terminals I ₁ and I ₂ .

That is, in this embodiment, the user is instructed to fully charge the battery 1 for the first time. Here, whether or not the battery 1 is fully charged is detected from -ΔV due to the decrease of the battery voltage from the peak value and the increase of the battery temperature. Note that it is not always necessary to detect both the battery voltage and the battery temperature as in this embodiment, and the full charge state may be detected by only one of them. Then, once fully charged, data indicating that the battery 5 is fully charged is written, and after the fully charged once, the charging control of the battery 1 is performed based on the remaining capacity as described above. To do. By doing so, it is possible to correct the error of the remaining capacity without unnecessary labor and cost. The capacity detection accuracy can be improved. At this time, since it is displayed on the display unit 4 that the battery 1 is fully charged, the user can certainly know that the battery 1 is fully charged.

By the way, in the above case, when the battery 1 is fully charged, the charging of the battery 1 is completely stopped.
In the case of rapidly charging the battery 1, it is preferable that after the battery 1 is completely charged, supplemental charging, that is, charging of a trickle current having a low current value is performed to fully charge the battery. Therefore, after the completion of charging when the battery 1 is rapidly charged, the transistor Q ₁ is turned on and off by the control circuit 3 so that the transistor Q ₂ is turned on and off to perform supplementary charging. Even if the battery 1 is charged with the pulsed current as described above, the battery 1
There is no problem because the charging of is done with the average current. The value of the trickle current can be gradually (stepwise in the case of the embodiment) reduced as shown in FIG. In this case, the on / off ratio may be varied to vary the high / low ratio of the control terminal C as shown in the second (b).

[0022]

As described above, according to the present invention, the remaining capacity detecting means for detecting the remaining capacity of the battery and the charging for controlling the battery charging state of the charger according to the remaining capacity detected by the remaining capacity detecting means. The control means is provided on the side of the battery pack to supply power to the remaining capacity detection means and the charge control means from the battery, and the control terminal is inserted in series in the charging path of the battery to set the control terminal to high and low.
The charger is provided with a switch element which is turned on / off by the output of the charging control means to be switched , and is detected by the remaining capacity detecting means.
Judgment hand to judge the operation control status of the charger from the remaining capacity
Control terminal of the charger according to the judgment result of the step and the judgment means
The charging circuit is controlled by a switch circuit that switches the
The control means is configured so that the output of the charge control means is in an output state in which the switch element is turned on except when the battery is fully charged. When connected, the charger is always in a state of supplying a charging current to the battery pack, so that the battery can be reliably charged even when the remaining capacity of the battery is small.

Further, a non-volatile storage means for storing whether or not the battery has been fully charged before, and a full-charge detection means for detecting that the battery has been fully charged are provided in the battery pack so that the battery is not fully charged for the first time. Until the battery is charged, if the charging control means controls the battery charge state of the charger according to the output of the full-charge detection means instead of the remaining-capacity detection output of the remaining-capacity detection means, the battery will be charged for the first time. In this case, by fully charging the battery, the remaining capacity detection error due to the remaining capacity of the battery can be corrected, and the remaining capacity detection accuracy can be improved.

Further, in supplementary charging after completion of charging of the battery in the case where the charger rapidly charges the battery, if the charging control means turns on / off the switch element to charge the battery with the trickle current, the charger is In the case of rapidly charging the battery, supplementary charging can be performed after the battery is completely charged.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a 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 completion of charging when rapid charging is performed in the above.

[Explanation of symbols]

A Battery pack B Charger 1 Battery 3 Control circuit 5 Memory 6 Switch circuit 7 Thermistor Q ₂ Transistor R ₀ Resistance

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-29079 (JP, A) JP-A 2-193533 (JP, A) JP-A 62-260533 (JP, A) SAIKAI HAI 3- 86744 (JP, U) Actual development Sho 61-29148 (JP, U) US Patent 4965738 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02M 10/42-10/48

Claims (3)

(57) [Claims] 1. A charging device comprising a battery pack mounted on a portable device and the like, and a charger for charging the battery when the battery pack is connected separately from the battery pack, The remaining capacity detection means for detecting the remaining capacity of the battery and the charging control means for controlling the battery charging state of the charger according to the remaining capacity detected by the remaining capacity detection means are provided on the battery pack side to detect the remaining capacity. Power is supplied from the battery to the means and the charging control means, and is inserted in series in the charging path of the battery ,
The charger is provided with a switch element that is turned on and off by the output of the charge control means that switches the control terminal to high and low .
Charger operation control based on the remaining capacity detected by the remaining capacity detection means
Judgment means to judge the state and the judgment result of the judgment means
Depending on the switch, the control terminal of the charger is switched between high and low.
The charge control means is configured by a switch circuit, and the output of the charge control means is in an output state that turns on the switch element except when the battery is fully charged. Charging device. 2. A battery pack is provided with non-volatile storage means for storing whether or not the battery has been fully charged before, and full-charge detecting means for detecting that the battery has been fully charged, so that the battery is not fully charged for the first time. Until charging, the charge control means controls the battery charge state of the charger according to the output of the full charge detection means, not depending on the remaining capacity detection output of the remaining capacity detection means. 1. The charging device according to 1. 3. The auxiliary charging after completion of charging of the battery when the charger rapidly charges the battery, wherein the charging control means turns on / off the switch element to charge the battery with a trickle current. The charging device according to claim 1.