JPH0799732A - Circuit for detecting detachment and attachment of battery - Google Patents

Abstract

PURPOSE:To reduce the number of the components of a circuit for detecting detachment and attachment of a battery and simplify the constitution of the circuit to provide the circuit at a low cost. CONSTITUTION:A current supply transistor 1 is connected between a DC power supply and a secondary battery for charging control and an apparatus 5 for detecting detachment and attachment of a battery is connected between the transistor 1 and the secondary battery. While the battery is charged, the transistor 1 is constantly turned on and off. While the transistor is in an off state, a voltage or a current is detected by the apparatus 5 for detecting dentachment and attachment of a battery and the detachment or attachment of the secondary battery is detected by the detected voltage or current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging circuit for a secondary battery, and more particularly to a battery attachment / detachment detection circuit for detecting attachment / detachment of a battery during charging of the secondary battery.

[0002]

2. Description of the Related Art In recent years, a battery attachment / detachment detection circuit provided in a charger is equipped with a method for detecting attachment / detachment of a battery by a level difference in voltage when a battery is inserted or not, or a mechanical contact switch. The method of detecting is used.

These conventional battery attachment / detachment detection circuits will be described below with reference to the drawings. FIG. 2 shows a conventional battery attachment / detachment detection circuit using a method for detecting attachment / detachment of a battery based on a voltage level difference between when the battery is inserted and when it is not attached. In FIG. 2, reference numeral 1 is a current supply transistor which forms a switch for charging or not charging the secondary battery,
It is always on during charging. 2 is a positive terminal for charging / discharging, which is connected to the positive terminal of the secondary battery,
Reference numeral 3 is a negative terminal for charging / discharging, which is connected to the negative terminal of the secondary battery. Reference numeral 4 is a regulator, which is an auxiliary power supply for transistors and ICs, 6 is a Zener diode for preventing backflow, and 7 is a resistor. Reference numeral 8 is a transistor that serves as an operation switch of the current supply transistor 1.

The operation of the battery attachment / detachment detection circuit configured to detect the attachment / detachment of the battery based on the voltage level difference will be described. First, the positive terminal of the secondary battery is connected to the positive terminal 2 for charging / discharging, and the negative terminal of the secondary battery is connected to the negative terminal 3 for charging / discharging, respectively. When desorbed, the current passes through the Zener diode 6 for backflow prevention and is connected to it.
The current flows to one resistor 7, and the transistor 8 which is the operation switch of the current supply transistor 1 is turned off by the voltage division of the two resistors 7.7. As a result, the attachment / detachment of the battery is detected, the current supply transistor 1 is turned off, and the charging of the secondary battery is stopped.

FIG. 3 shows a conventional battery attachment / detachment detection circuit using a method of detecting attachment / detachment of a battery by a mechanical contact switch. In FIG. 3, 1 to 8 are composed of the same parts as in FIG. 2, and 9 is a mechanical contact switch.

The operation of the battery attachment / detachment detection circuit, which is detected by using the mechanical contact switch 9 configured as described above, will be described. First, the positive terminal of the secondary battery is connected to the positive terminal 2 for charging / discharging, and the negative terminal of the secondary battery is connected to the negative terminal 3 for charging / discharging, respectively. When detached, the mechanical contact switch 9 is turned off, and the transistor 8 which is the operation switch of the current supply transistor 1 is turned off. As a result, the attachment / detachment of the battery is detected, and the current supply transistor 1
Turns off and charging stops.

[0007]

However, in the conventional circuit for detecting the attachment / detachment of the battery based on the voltage level difference as described above, the voltage at the time when the secondary battery is detached and unloaded and when the secondary battery is inserted is attached. The detection range must be assumed in advance and set to a voltage higher than the maximum voltage during charging. Further, in the method of detecting using a mechanical contact switch, a switch is required in addition to the charging terminal, which complicates the circuit configuration. Further, with the above configuration, both of these methods have a problem of high cost.

The present invention solves such a problem, and provides a battery attachment / detachment detection circuit which is inexpensive, has a simple circuit configuration, and has a function of checking the battery voltage and current at any time during charging. That is the purpose.

[0009]

In order to solve these problems, a battery attachment / detachment detection circuit of the present invention comprises a current supply transistor connected between a DC power supply and a secondary battery for controlling charging, and A battery attachment / detachment detection circuit comprising a battery attachment / detachment detection device connected between a current supply transistor and a secondary battery, wherein the current supply transistor is constantly turned on and off during charging, and the current supply transistor is turned off. At this time, the voltage or current is detected by the battery attachment / detachment detecting device, and the fact that the secondary battery is attached or detached is detected by this voltage or current.

[0010]

According to the battery attachment / detachment detection circuit configured as described above, the number of circuit components for detecting attachment / detachment of the battery can be reduced and the circuit configuration can be simplified. There is an advantage that it can be configured only with an auxiliary power supply for driving a transistor without using two types of power supply lines for the auxiliary power supply, and can be used as a means for constantly confirming the state of battery attachment and detachment.

In addition, when the secondary battery is being charged, the current supply transistor is constantly turned on and off,
Since the battery voltage can be detected when the battery is off, the battery status can be constantly checked.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a battery attachment / detachment detection circuit according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a current supply transistor which serves as a switch for charging or not charging the secondary battery. 2 is a positive terminal for charging / discharging, which is connected to the positive terminal of the secondary battery, and 3 is a negative terminal for charging / discharging, which is connected to the negative terminal of the secondary battery. Reference numeral 4 is a regulator, which is an auxiliary power source such as a transistor or an IC. 5 is a battery attachment / detachment detection device, 6 is a Zener diode for preventing backflow, and 7
Is resistance.

The operation of the battery attachment / detachment detection circuit of the present embodiment configured as described above will be described. In this circuit, the positive terminal of the secondary battery is connected to the positive terminal 2 for charging / discharging, and the negative terminal of the secondary battery is connected to the negative terminal 3 for charging / discharging. The transistor 1 is always turned on and off, and the battery voltage can be detected when it is turned off. When the secondary battery connected here is detached and the battery voltage cannot be detected when the current supply transistor 1 is off, the current passes through the backflow preventing Zener diode 6 and passes through the battery attaching / detaching device 5 The battery supply transistor 1 is turned off and the charging is stopped.

[0015]

As described above, the configuration of the battery attachment / detachment detection circuit provided with the battery attachment / detachment detection device of the present invention can reduce the number of circuit components and simplify the circuit configuration, and provide an inexpensive battery attachment / detachment detection circuit. Obtainable. Further, since the battery voltage is constantly detected during charging, it is possible to immediately stop charging even when an abnormal current flows in the battery.

[Brief description of drawings]

FIG. 1 is a diagram showing a battery attachment / detachment detection circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional battery attachment / detachment detection circuit.

FIG. 3 is a diagram showing a conventional battery attachment / detachment detection circuit.

[Explanation of symbols]

 1 Battery Supply Transistor 2 Charging / Discharging Positive Terminal 3 Charging / Discharging Negative Terminal 4 Auxiliary Power Supply 5 Battery Attachment / Detachment Detection Device 6 Zener Diode 7 Resistance 8 Battery Detection Transistor 9 Mechanical Contact Switch

Claims (1)

[Claims] 1. A battery comprising: a current supply transistor connected between a DC power supply and a secondary battery for controlling charging; and a battery attachment / detachment detection device connected between the current supply transistor and the secondary battery. A desorption detection circuit, in which the current supply transistor is constantly turned on and off during charging, and when the current supply transistor is off, the battery desorption detection device detects voltage or current, and the secondary battery is detected by this voltage or current. Battery removal detection circuit that detects that the battery has been removed.