JPS59159633A - Charging device - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a charging device with a battery voltage drop warning device.

[Background technology]

FIG. 1 shows a block diagram of this type of charging device that has been conventionally used. Input from commercial AC power supply (AC input)
The voltage is divided by the transformer T, full-wave rectified by the rectifier Rec, and the battery, BT, is charged via the charging current limiting resistor RO. A voltage monitoring unit 1 connected in parallel to the battery BT turns on a light emitting diode (LED) when the voltage of the batch IJ-BT drops and reaches a preset voltage VTR.
) lights up to warn of low battery voltage.

In the case of this charger circuit, the output voltage VA of the transformer T is fixed, and the impedance when looking at the input side from the battery BT is determined by the resistor RO, so the following phenomenon occurs. That is, the charging current to be charged to the battery BT is IBT, and the current Ic consumed by the voltage monitoring section is
e. If the LED current when the LED lights up is ILED, then IBT -) - ICC + ILED = k (k:
A relational expression (constant) holds true. In other words, the total current of this circuit is determined by the resistor Ro and the output voltage VA of the transformer T. At this time, assuming that the current consumption of the voltage monitoring unit 1 is constant, when the LED is on and when the L
When the ED is off, the charging current IE to the battery BT
T will change. That is, when the LED is turned on, the charging current IBr is small, and when the LED is off, the charging current IBr is small.
This means that BT becomes large.

In this way, when the LED is turned on or off, if the charging current IET changes, the time it takes for the batch IJBT to go from the discharged state to the fully charged state, ie, the charging time, changes. In particular, since the charging current IBT decreases when the LED is turned on, the charging time becomes longer, and the charging time in this state is extended by about 10%.

If the charging time changes in this way, the charging time must be specified for quality control of the charging device, but it is difficult to set the charging time.

2. When this circuit is applied to products stipulated by law, such as emergency lights, it will not only violate the law due to changes in charging time, but also cause the emergency lights to fail to turn on in an actual emergency. This may result in serious inconvenience.

There were serious drawbacks in terms of reliability.

The present invention has been made in view of this point.

[Purpose of the invention]

The present invention relates to a charging device equipped with a battery voltage drop warning device, and its purpose is to maintain a constant charging current to the battery regardless of whether a warning light emitting diode (LED) of the warning device is turned on or off. An object of the present invention is to provide a charging circuit that can be controlled so that

[Disclosure of the invention]

■Structure of the Invention The gist of the present invention is to provide a charging circuit that rectifies a commercial AC input power source, current-limits it using a charging current control resistor, charges a secondary battery, and constantly monitors the voltage of the secondary battery. The above-mentioned warning signal is issued in a charging device equipped with a voltage monitoring circuit that issues a warning signal when an abnormality such as an abnormal drop or rise in battery voltage occurs. This charging device is configured so that the charging current for the secondary battery is controlled to be substantially constant regardless of whether the secondary battery is charged or not.

(2) Examples of the Invention The present invention will be explained using examples. FIG. 2 is a circuit diagram showing an embodiment of the charger according to the present invention.

This part shows the voltage monitoring section 1 and the LED part in FIG.

In FIG. 2, the terminal ■ is connected to the battery BT+ terminal in FIG.

Battery BT voltage VDT is divided by resistors R1+R2, and the voltage at the voltage dividing point is connected to the base of transistor QI. Similarly, the voltage V is applied to the base of transistor Q2.
The anode of a diode D1 in a series circuit of a resistor R6 and diodes D1 and D2 is connected to BT. The diodes DI and D2 form a reference voltage circuit. That is, since the forward voltage drop of a diode is constant at about 0.6V, two of these are connected in series to obtain a reference voltage of 1.2V.

It should be noted that, of course, other circuit configurations may be used instead of the reference voltage source.

Transistor Q1. The emitters of Q2 are connected together,
A resistor R5 is connected between this connection point and the ground terminal.
It will be done. The collectors of transistors Ql and Q2 are connected to terminal 2 via resistors R3 and R4, respectively.

P from the connection point of resistor R4 and collector of transistor Q2
NP The base of transistor Q4 is connected to the emitter terminal of transistor Q4, and the collector is connected to resistors R7 and R8.
connected to the ground terminal through a series circuit. resistance R7,
The gate of a thyristor (SCR) Q6 is connected to the connection point of Rs, the cathode of the thyristor Q6 is connected to the ground terminal, and the anode of the thyristor Q6 is connected to the cathode of the LED via a resistor R9.

The anode of the LED is connected via the switch S to the terminal ■. On the other hand, from the collector of transistor Q1, PNP
) The base of transistor Q8 is connected, the emitter of Q3 is connected to terminal ■, and the collector of PNP transistor Q3 is connected to resistor R.
It is connected to the ground terminal via a series circuit of IO and R11. The base of a transistor Q5 is connected to the connection point between the resistors RIO and R11, the emitter of Q5 is connected to the ground terminal, and the collector thereof is connected to the terminal (2) via the resistor R12. In this circuit, a pair of transistor resistors Q4, R7, Re Qa, a transistor, resistors Q3, RIO, R11, Q
The pairs of s form a symmetrical circuit.

In the operating state of the plate, in Figure 2, the voltage division ratio of resistors R1 and R2 is set to the warning voltage V.
TH is set in advance so that it has the same potential as the reference voltage (base voltage of transistor Q2) at the base of transistor Qt. Also, switch S is normally open.

When the battery voltage VBT') is the warning voltage VTH, the comparator composed of transistors, resistors Ql, Q2, R3R4, and R5 turns on transistor Ql and turns Q2 on because the base potential of transistor Q1 is higher than the base potential of transistor Q2. It turns off. Therefore, transistor Q3 is turned on, transistor Q5 is turned on, and current flows from terminal A through resistor R12. This current I
l is calculated by the following formula.

However, VCE(SAT)Q5 is the saturation voltage between the collector and base of transistor q5.

Batch IJ 11 voltage VBT (When warning voltage VrH, transistor, resistor Ql, Q2, R8, R4, R
Since the base potential of the transistor Q1 is lower than the base potential of the transistor Q2, the transistor 91 is turned off and the transistor 92 is turned on. Therefore, the transistor Q4 is turned on, the thyristor Q6 is turned on, and a current flows from the terminal (2) through the LED and the resistor R9.

The resistor R9 is a limiting resistor for limiting the current ILED flowing through the LED. Current at this time ILED = I2
is expressed by the following equation.

However, in this circuit, when the thyristor Q6 is triggered, it continues to be on, and even if the battery voltage VDT returns to the warning voltage VTR or higher again, the LED continues to light up. .

Therefore, the currents I, , I2 in the above ■ and ■ are 11=12
If you control it so that it will, the LED will light up.

Regardless of whether the light is turned off or not, the current flowing into this circuit from terminal (2) will not fluctuate. Therefore, the condition is I, =
12, it is sufficient to configure the structure so that the ratio of R12 and R9 is obtained. By doing this, the following formula
In IBT = k - (ICC + ILED), I
Since ce −1−ILED can be kept constant, IBT
is the LED on, and the switch S is a reset switch. When the switch S is turned off, the ED goes out and the thyristor Q6 is turned off. When the switch S is turned on again, if the battery BT has a normal voltage, the LED will turn off. Continues to be off.

〔Effect of the invention〕

According to the present invention, since the charging current to the battery can be controlled to be substantially constant regardless of whether the LED that warns of battery voltage drop is on or off, a stable charging state can be obtained without changing the charging time. This has a great effect on quality assurance when used for emergency lights, etc.

[Brief explanation of the drawing]

FIGS. 1 and 2 are circuit diagrams showing one embodiment of the present invention. Patent applicant Matsushita Electric Works Co., Ltd. Representative patent attorney Toshimaru Takemoto (and 2 others)

Claims (1)

[Claims] (1) A charging circuit that full-wave rectifies the commercial AC input power supply, current-limits it with a charging current control resistor, and charges the secondary battery, and constantly monitors the voltage of the secondary battery to prevent abnormal drops or increases in battery voltage. The above-mentioned warning signal is issued in a charging device equipped with a voltage monitoring circuit that issues a warning signal when an abnormality occurs. A charging device configured to control the charging current of the secondary battery to be substantially constant regardless of whether the secondary battery is charged or not.