JPS6377331A - Battery charger - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] g) Technical field of application The present invention relates to a charging device for a secondary battery such as a nickel-cadmium battery, and more particularly to a charging control system that detects the end of charging of the battery based on the elapsed time of a timer. This is related to the improvement of the method.

(b) Prior art As one method for detecting the end of charging of a secondary battery, a timer circuit that operates simultaneously with battery charging is provided in the charging circuit, and when the timer circuit reaches a predetermined time, the battery There is a way to stop the current supplied to the

For example, the timer device of a charger disclosed in Japanese Patent Application Laid-open No. 58-33942 is one example of a charger having two sets of charging sockets to which two sets of battery packs are individually connected and simultaneously supplied with power. , a time constant circuit in which two resistors and a capacitor are connected in series, and a normally closed switch that opens when the two battery packs are connected to a charging socket is connected in parallel to one of the resistors, and a set time of the circuit. a timer circuit that oscillates in response to the oscillation output and generates a predetermined output by counting the oscillation output; and a reset circuit that generates a reset signal to reset the timer circuit when at least one set of battery packs is connected to a charging socket. It is prepared. In this type of conventional circuit, the holding voltage of capacitor C1 in Fig. 1 is designed to prevent the timer circuit from resetting in the event of a momentary power failure, but when the power supply voltage is no longer applied, capacitor CI is charged. Since the charge is discharged to the timer circuit side through the collector and emitter of the transistors that make up the constant voltage circuit, unless the capacitance of the capacitor C1 is quite large, the stored charge in the capacitor C1 will be consumed immediately, and the timer will not function properly when the power supply is interrupted. The problem is that it does not serve as a protection measure for the circuit.

C→ Problem to be Solved by the Invention The problem to be solved by the present invention is to develop a new protection circuit for the timer circuit and use it in a battery charging device to prevent the power supply from momentarily turning off during battery charging. To complete charging of a battery without error even if the battery is disconnected.

B) Means for solving the problem: A DC power supply, a battery to be charged connected to the DC power supply, and a timer circuit connected in parallel to the battery and bypassing the charging current when the battery is fully charged. In the charging device equipped with
A collector and an emitter circuit of a first transistor are connected in parallel to the battery and the timer circuit, and a capacitor is provided between the base and the emitter of the first transistor to hold the voltage applied to the transistor when the DC power supply is momentarily cut off. A delay circuit made of a resistor is connected, and a collector and emitter circuit of a second transistor whose base is connected to the collector and emitter circuit of the first transistor is inserted between the positive electrode of the battery and the timer circuit.

(E) Function The capacitor of the delay circuit maintains the voltage when the power supply is momentarily cut off, and the i
Both @1 and the second transistor are held in a conductive state.

The timer circuit is therefore supplied with current from the battery through the second transistor, preventing its reset.

(F) Embodiment Hereinafter, the battery charging device of the present invention will be explained in detail with reference to an implementation circuit diagram of FIG. 1 and a circuit operation explanatory diagram of FIG. M2.

In the 11th leap, DC is a direct current power supply, -next:+Ile L1 is a commercial alternating current (ACINP (rT 1067/IA)
A step-down transformer T that receives all inputs, a t41 that is connected to both ends of the secondary coil L2 of the transformer τ, and whose anodes are connected to form one output terminal, and a second rectifier DI.
, D2, and the other output terminal is connected to the intermediate tap of the secondary coil L2.

It is connected between the power terminals via a backflow prevention diode D4.

Ql is a first transistor whose collector and emitter circuits are connected in parallel between the positive and negative electrodes of the battery via a resistor R6. A delay circuit consisting of a capacitor C1 and a resistor R2 is connected between the base and emitter of the first transistor Q1 in order to set a short period of time from immediately after the power supply DC is turned on until charging of the battery B starts. Further, a connection point between the capacitor C1 and the resistor R2 is connected to one output terminal of the DC power supply DC via the resistor R1.

Further, the collector of the first transistor Q1 is connected to one output terminal of the DC power supply DC via a diode D3 and a resistor R3.

TC is a timer circuit that detects the time TR from the time of complete discharge to the time of full charge of the battery B and bypasses the charging current to stop supplying the charging current to the battery B when the battery B is fully charged; It is connected in parallel between the positive and negative electrodes of the battery B via the emitter and collector of the second transistor q2. This timer circuit TC mainly includes a timer IC that operates using the output voltage of the DC power supply DC or the output voltage of the battery B as VCC,
The first bin of the timer C is connected to the negative electrode of the battery B via a capacitor C2, the second bin is connected to the collector of the second transistor Q2 via a resistor R4,
The No. 4 pin is directly connected to the negative electrode of the battery B, and the No. 4 pin is connected to the negative electrode of the battery B via a capacitor C3.
It is connected to the negative electrode of the battery B via the No. 5 pinning resistor RIG. Further, the first pin and the fourth pin are connected through a resistor R5. Note that the sixth bin also serves as an input terminal for inputting the output voltage VQc of the power source DC-i or the battery B.

RD is a charging display circuit that displays the charging state of the battery B, and includes nine light-emitting diodes LED, a resistor R9, a third transistor q3, and a third transistor connected in series between both output terminals of the DC power source DC. Between the base of Q3 and the anode of the light emitting diode IJKD, the light emitting diode L! ! ! Resistors Ry and R connected in parallel to DK
g. The fifth bin of the timer circuit C of the timer circuit TC is connected to the midpoint between the resistors R7 and R8 via a resistor R11.

MF! A drive motor is connected between the positive and negative terminals of the battery B via a starting switch 8, and the positive terminal of the motor X is connected to the light emitting diode I via diodes D5 and D6.
l! : Connected to the anode side of D.

The operation of the battery charging device MK having the above configuration will be explained in detail based on Figure 1.2. The implementation circuit shown in Figure 1 is a motor-driven device using a type of rechargeable battery.
It is assumed that battery B and motor M are installed in the device.

Charging of the battery B is started by inputting commercial AC to the primary coil LIK of the step-down transformer T of the DC power supply 'DC. The first transistor QIFi detects when the DC power supply DC is turned on, and immediately after turning on, it becomes non-conductive due to the delay circuit (time to in FIG. 2).

Eventually, the capacitor C1 of the delay circuit is charged, and about 3 seconds after the power is turned on (time 1+ in FIG. 282), the first transistor Q1 becomes conductive. Therefore 1@2 transistor c
The base potential of L2 changes from Hlgh to Low, and the second
Transistor q2 becomes conductive. The output voltage Vaa is applied to the timer CK from the DC power source DC via the second transistor q2 which is turned on in this way, and the resistor R4
The input current is supplied to the second terminal through the timer IC.
is set and starts counting the elapsed time. Resistor R5 and capacitor C3 constitute a constant that determines the set time of the timer IC, and serve as a stabilizing capacitor C2/d. The output from the fifth pin of the timer IC changes from LOW to HIGH at the same time as charging starts, and the base current is supplied to the third transistor Q3 of the charging display circuit, making the third transistor Q3 conductive. Therefore, the light emitting diode (LKI) is lit by the output current from the DC power supply DC to indicate that charging is in progress.

When the set time t of the timer IC is reached at time t4, the output of pin 5 of the timer IC changes from Hlgh to IJQ.
The display changes to W, and a message indicating that battery B has been charged is displayed. If the connection between the commercial power source and the step-down transformer T is cut off at this point, the voltage Vaa will no longer be supplied and the timer IC will be reset to its initial state.

Consider the case where the DC power supply 'DC is momentarily cut off at current side t2. At this time, the first transistor Q1 is connected to the capacitor CI
The voltage VCC is applied from the battery B to the timer C via the second transistor Q2. Therefore, the timer operation continues.

Note that when the timer IC is not operating, that is, when the motor M is being driven by turning on the switch S, the diode D3 is connected to prevent the current from the battery B from being consumed in the charging circuit. It's a special thing. Also, while the motor M is driving, the resistor R7 is connected via the diodes D5 and D6.
A current flows through R8, which makes the third transistor Q3 conductive and lights up the light emitting diode LED.

(G) Effects of the Invention As described above, the present invention comprises a DC power supply, a battery to be charged connected to the DC power supply, and a timer connected in parallel to the battery to bypass the charging current when the battery is charged. In a charging device comprising a circuit, the collector and emitter circuits of a first transistor are connected in parallel to the battery and the timer circuit, and when the DC power is cut off between the base and emitter of one transistor, the transistor A delay circuit consisting of a capacitor and a resistor that holds the applied voltage is connected, and a collector and emitter circuit of two transistors whose bases are connected to the collector and emitter circuit of the first transistor is connected between the positive electrode of the battery and the timer circuit. By inserting the capacitor, the amount of charge on the capacitor (gl) is sufficient to keep the transistor in a conductive state, and the effect is that a capacitor with a small capacitance can be used.

[Brief explanation of the drawing]

FIG. 1 is an implementation circuit diagram of the battery charging device of the present invention, and FIG.
The figure is an explanatory diagram of the operation. DC...DC power supply, B...Battery to be charged, TC...
Timer circuit Lct, l... gl) transistor, CI river capacitor, R2... resistor, Q2... second transistor.

Claims (1)

[Claims] (1) A charging device comprising a DC power supply, a battery to be charged connected to the DC power supply, and a timer circuit connected in parallel to the battery and bypassing the charging current when the battery is fully charged. A collector and an emitter circuit of a first transistor are connected in parallel to the timer circuit, and a capacitor and a resistor are provided between the base and emitter of the first transistor to maintain the voltage applied to the transistor during a momentary interruption of the DC power supply. A battery characterized in that a delay circuit is connected and a collector and emitter circuit of a second transistor whose base is connected to the collector and emitter circuit of the first transistor are inserted between the positive electrode of the battery and the timer circuit. Charging device.