JPH099519A - Charger - Google Patents

Abstract

PURPOSE: To provide a charger enabling easy recognition of the kind of a battery incorporated in a battery pack, even when the kind is discriminated automatically falsely. CONSTITUTION: In a charger which discriminates automatically the kind of a secondary battery 25 on the basis of the electrical characteristics of a battery pack 20 wherein the battery 25 is incorporated, and executes charging on the basis of the result of the discrimination according to a charging control system being suitable for the kind of the battery 25, LEDs 3, 4 and 5 for indicating the kind of the battery 25 on the basis of the result of the discrimination of the kind of the battery 25 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger for charging a secondary battery in a battery pack used in a device such as a mobile phone, and in particular, a battery in the battery pack is a nickel-cadmium storage battery, a nickel-hydrogen storage battery, The present invention relates to a charger compatible with various types of battery packs such as lithium-ion secondary batteries.

[0002]

2. Description of the Related Art Secondary batteries such as nickel-cadmium storage batteries, nickel-hydrogen storage batteries and lithium-ion secondary batteries are cordless type consumer products typified by portable personal computers, mobile phones, video cameras and the like, which are aimed at downsizing and weight reduction. It is often used as a power source for equipment.

Recently, a plurality of types of battery packs having different types of built-in batteries have been prepared as battery packs corresponding to one applied model. For example, among mobile phones, low-priced ones have a nickel-cadmium storage battery built-in, high-capacity ones have a nickel-hydrogen storage battery built-in, and small and lightweight ones have a lithium-ion secondary battery built-in battery pack. In this way, the user can use the battery pack properly according to the purpose.

As described above, when a plurality of types of battery packs having different built-in batteries are prepared for one applied model, it is desired that the charger be a battery charger that can be shared by these battery packs. In such a charger, the optimal charging control method for the battery differs depending on the type of battery pack, so when the battery pack is set in the charger, the type of battery pack, that is, the type of built-in battery is automatically determined first. , It is necessary to select a charging control method suitable for the battery and perform charging.

Conventionally, various methods have been considered as methods for automatically determining the type of battery pack (type of built-in battery). For example, in Japanese Unexamined Patent Publication No. 2-299428, as shown in FIG. 2, a battery discriminating resistor 27 having an arbitrary value is provided in a battery pack 20 and both ends thereof are connected to a negative terminal 22 of a battery 25 and a discriminating output terminal 24. Then, the charger detects the value of the resistor 27 via the terminals 22 and 24, and the type of the battery pack 20, that is, the secondary battery 2 is detected from the detected resistance value.
There is disclosed a charger configured to automatically discriminate 5 types.

Further, in Japanese Unexamined Patent Publication No. 7-31071, the internal impedance of the secondary battery 25 in FIG. 2 is measured via a plus terminal 21 and a minus terminal 22, and the type of the battery pack 20, that is, the battery, is determined from the impedance value. Two
There is disclosed a charger configured to automatically discriminate 5 types.

All of these methods are methods for automatically determining the type of the built-in battery by utilizing the electrical characteristics of the battery pack. In addition to this, the type of the battery can be determined from the bar code attached to the battery pack. There is also a so-called mechanical determination method in which automatic determination is performed or the outer shape of a battery pack is made different to automatically determine the type of battery from the shape. However, in the latter mechanical automatic identification method, since an additional circuit other than the charging circuit and a detection unit are added in the charger, it is not practical from the viewpoint of increasing the size of the charger or increasing the price, The automatic identification method utilizing the former electrical characteristics is widely used.

[0008]

In the battery charger which automatically determines the type of the built-in battery by utilizing the electrical characteristics of the battery pack described above, as described with reference to FIG. The type of the built-in battery is automatically determined by detecting the resistance value and the battery impedance provided in the battery pack. Therefore, if the terminals of the battery pack are dirty or deteriorated, or if the terminals of the battery pack and the terminals on the charger side do not contact properly, make sure that the terminals of the battery pack and the terminals on the charger side are The contact resistance between them may change, and due to the influence, the automatic determination of the battery type may be erroneous. Further, there is a possibility that the automatic determination of the battery type may be erroneous due to a wrong mounting of the resistor at the time of manufacturing the battery pack, a poor connection of the resistor, or a change in the internal impedance due to deterioration of the battery itself.

As described above, if the charger performs charging while erroneously discriminating the type of the battery contained in the battery pack, the battery in the battery pack is charged by the charging control method which is not suitable for the type of the battery. There are problems that the battery is not charged, the battery deteriorates quickly, and in the worst case, the battery explodes. It is an object of the present invention to provide a battery charger that can easily recognize the type of a battery built in a battery pack even if the battery type is automatically identified by mistake.

[0010]

In order to solve the above problems, the present invention automatically determines the type of the secondary battery from the electrical characteristics of the battery pack containing the secondary battery, and determines based on the determination result. In a charger for charging a secondary battery according to the charging control method described above, the battery type display means for displaying the type of the secondary battery incorporated in the battery pack based on the type determination result of the secondary battery is characterized. And This battery type display means selectively displays light emitting elements such as LEDs provided corresponding to the types of secondary batteries such as nickel-cadmium storage batteries, nickel-hydrogen storage batteries, and lithium-ion secondary batteries, The battery type shall be displayed.

[0011]

With the charger of the present invention having the above-described structure, the type of the battery pack being charged, that is, the type of the battery contained in the battery pack can be easily recognized from the outside. Even when the container misjudges the type of the battery pack and starts charging, the user can immediately recognize the misjudgment and stop the charging.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a charger according to an embodiment of the present invention, and FIG. 3 is an external view of a charger and a battery pack.

The charger shown in FIG. 1 comprises a charging control circuit 1 connected to a charging power source + V and a microcomputer 2
, The LEDs 3, 4, 5 and the external connection terminals 11, 12, connected to the AND circuits 6, 7, 8 and the battery pack 20,
It consists of 13 and 14. The terminal 11 is a positive charging terminal, the terminal 12 is a negative charging terminal, the terminal 13 is a temperature measurement input terminal, and the terminal 14 is a discrimination input terminal. The microcomputer 2 mainly comprises a battery type determination unit 2a, a charging control unit 2b, and an LED display control unit 2c.

The LEDs 3, 4, and 5 are provided in the housing 30 of the charger as shown in FIG. 3, and are for displaying the type of the secondary battery 25 incorporated in the battery pack 20.
It is assumed that D3 corresponds to a nickel-cadmium storage battery, LED4 corresponds to a nickel-hydrogen storage battery, and LED5 corresponds to a lithium-ion secondary battery.

On the other hand, the battery pack 20 charged by the charger has a secondary battery 25, a thermistor 26, a battery discriminating resistor 27 and external connection terminals 11, 12, 13, 14 of the charger at the time of charging, respectively. The external connection terminals 21, 22, 23, and 24 are connected. The terminal 21 is a plus terminal 21, the terminal 22 is a minus terminal, the terminal 23 is a temperature measurement output terminal, and the terminal 24 is a discrimination output terminal. The secondary battery 25 includes, for example, types of nickel-cadmium storage battery, nickel-hydrogen storage battery, and lithium-ion secondary battery, and the battery discrimination resistor 27 is set to a resistance value having a size corresponding to these types of batteries. For example, the resistance value of the battery discriminating resistor 27 is set such that the battery 25 is 1 kΩ when the battery is a nickel-cadmium storage battery, 10 kΩ when it is a nickel-hydrogen storage battery, and 50 kΩ when it is a lithium ion secondary battery.

Next, the operation of the charger of this embodiment will be described. When the battery pack 20 is set in the charger, the battery type determination unit 2a of the microcomputer 2 causes a current to flow between the determination output terminal 24 and the negative terminal 22 of the battery pack 20 to cause the voltage drop of the battery determination resistor 27. By detecting, the type of the battery 25 is determined. That is, since the resistance value of the battery discriminating resistor 27 is changed depending on the type of the battery 25 as described above, the battery type discriminating unit 2a can discriminate the type of the battery 25 from the difference in the voltage drop of the resistor 27. As a result of this determination, the battery type determination unit 2a determines that the battery 2
The discrimination output corresponding to the five types is sent to the charging control unit 2b.

The charging control unit 2b outputs a charging control signal suitable for the type of the battery 25 in the battery pack 20 to the charging control circuit 1 based on the discrimination output from the battery type discrimination unit 2a. Here, the charging control unit 2b has three output lines 9a, 9b, 9c as signal lines for outputting a charging control signal, the output line 9a for nickel-cadmium storage battery and the output line 9b for nickel-hydrogen storage battery. The output line 9c is for a lithium ion secondary battery.

The charging control circuit 1 uses these output lines 9a,
Based on the charge control signal input via 9b and 9c, charge control is performed by a method suitable for the type of the battery 25 in the battery pack 20. Specifically, for example, when the battery 25 is a nickel-cadmium storage battery, the battery 2 is charged with a constant current.
When the terminal voltage of 5 drops by a predetermined value (ΔV), the charging current is stopped or reduced, and the charging control is performed by “−ΔV control”. When the battery 25 is a nickel-hydrogen storage battery, it is charged with a constant current to increase the battery temperature (so-called temperature differential).
The charging control is performed by "dT / dt control" that stops or decreases the charging current when reaches a predetermined value. Furthermore, when the secondary battery 25 is a lithium-ion secondary battery, the battery is charged at a constant current in the initial charging, and the battery voltage has a predetermined value (for example, 4.2 V).
/ Cell), the charging is controlled by "constant current / constant voltage charging", which charges at a constant voltage.

On the other hand, the LED display control section 2c outputs a light emission control signal for selectively causing one of the LEDs 3, 4, 5 to emit light based on the discrimination output from the battery type discrimination section 2a. Here, the output terminal of the LED display controller 2c and L
Between the EDs 3, 4 and 5, AND circuits 6, 7 and 8 which take a logical product of the light emission control signal from the LED display control section 2c and the charge control signal on the output lines 9a, 9b and 9c are inserted. The LED corresponding to the determined battery is configured to emit light.

For example, when the battery type discriminating unit 2a discriminates the battery 25 of the battery pack 20 as a nickel-hydrogen storage battery, the charging control unit 2b controls the charging control circuit 1 with only the output line 9b in the ON state. When the output line 9b is turned on,
When the light emission control signal is output from the LED display control unit 2c, the output of the AND circuit 7 is turned on, and the nickel hydride storage battery LED 4 emits light. At this time, the other output line 9
Since a and 9b are in the OFF state, the outputs of the AND circuits 6 and 8 remain OFF even when the light emission control signal is output from the LED display control unit 2c, and the LED 3 for the nickel-cadmium storage battery and the lithium-ion secondary battery. LED for battery
5 does not emit light.

In the above-described embodiment, the type of the battery 25 is discriminated by the difference in the resistance value of the battery discriminating resistor 27, but the discriminating means of the battery type is not limited to this, and other discriminating means may be used. The present invention can be applied when used.

[0022]

As described above, according to the charger of the present invention, when the battery in the battery pack is charged, the type of the battery to be charged can be easily recognized from the outside by the light emission of the LED or the like. it can. Therefore, even if the charger mistakenly identifies the type of battery pack, it can be easily determined from the outside, so it is possible to take appropriate measures such as immediately stopping charging, and the battery pack may burst.・ It is possible to avoid danger such as ignition and explosion.

[Brief description of drawings]

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

FIG. 2 is an internal circuit diagram of a battery pack having a battery discrimination resistor built-in.

FIG. 3 is an external view of a charger according to the embodiment.

[Explanation of symbols]

 1 ... Charging control circuit 2 ... Microcomputer 3, 4, 5 ... LED 6, 7, 8 ... AND circuit 9a, 9b, 9c ... Output line 11 ... Positive charging terminal 12 ... Negative charging terminal 13 ... Temperature measurement input terminal 14 ... discrimination input terminal 20 ... battery pack 21 ... plus terminal 22 ... minus terminal 23 ... temperature measurement output terminal 24 ... discrimination output terminal 25 ... secondary battery 26 ... thermistor 27 ... battery discrimination resistor 30 ... charger housing

Claims (2)

[Claims] 1. A charging method in which a type of the secondary battery is automatically discriminated from the electrical characteristics of a battery pack containing the secondary battery, and the secondary battery is charged by a charging control method determined based on the discrimination result. The battery charger includes a battery type display unit that displays a type of a secondary battery built in the battery pack based on the determination result. 2. The battery type display means displays the type of the secondary battery by selectively displaying a plurality of light emitting elements provided corresponding to the type of the secondary battery. The charger according to claim 1, wherein: