JPS61124236A - Detecting circuit for state of charging of battery - 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 (Field of Industrial Application) The present invention relates to a charging display circuit for determining whether charging is in progress or charging is complete when charging a nickel cadmium battery.

(Prior Art) Conventionally, devices such as electric cleaners and electric drills equipped with battery-driven motors have an electric circuit as shown in FIG. An AC adapter ADP that outputs a low-voltage DC power supply corresponding to battery B1 charging via the bridge DBI and smoothing capacitor C1, etc., a charging current limiting resistor R1, a battery B1 power supply connection to the motor M1, and an AC adapter ADP to the battery B1. The motor M1 is driven by switching the switch SWI to the motor starting side, and the switch SW1
By switching to the battery charging side, battery B1
In this format, it takes 3 times for charging.
Although it takes ~6 hours, the charging circuit is inexpensive because it uses a stray charging type to prevent explosions and leakage due to overcharging even if the charging time exceeds a little.

However, in this case, it is not possible to know the charging status, and the only way to determine whether it is fully charged is by checking the watch.
As a result, the battery may run out earlier than expected if the device is used while uncharged, or conversely, the device may continue to charge for hours even though it was fully charged in a short time, wasting power during that time. There was a drawback that I had to do it.

(Problems to be Solved by the Invention) An object of the present invention is to make it possible to easily check whether a nickel-cadmium battery is being charged before being fully charged or is in a fully charged state at the completion of charging during charging.

(Means for Solving the Problem) The present invention includes a voltage change detection circuit that changes the output voltage according to a change in the charging voltage of a nickel-cadmium battery, and a peak voltage holding circuit that maintains the voltage at the maximum charging voltage of the nickel-cadmium battery. , a voltage discriminator that compares the charge change voltage from the voltage change detection circuit and the charge peak voltage from the peak voltage holding circuit and changes the output when the charge peak voltage becomes higher than the charge change voltage; and a charge state display circuit that changes the lighting state from one of on and off to the other according to the output from the voltage discriminator when the peak voltage becomes higher than the charge change voltage. .

(Embodiment) Next, the configuration of an embodiment of the present invention will be described with reference to FIGS. 2 to 5.

Terminals TI and T connected to an AC power adapter (not shown)
A nickel cadmium battery B2 is connected between the two via a forward diode D1, and voltage dividing resistors R2 and R3 as a voltage detector 1 for detecting the power supply voltage V1 are connected, so that the power supply voltage 1 is The collector of the transistor Q1 connected to the midpoint between the voltage dividing resistors R2 and R3, which is turned on by supplying voltage, is a switching means for controlling the output of the battery B2 on and off, in this case resistors R4 and R5 and the transistor Q2. A voltage discriminator 3, a memory circuit 4, and an oscillation drive circuit 5 for blinking an LED as an indicator light are connected to the base of the transistor Q2 of the switching means 2, which is connected via a resistor R4, to the collector of the transistor Q2. are connected to each other.

That is, the switching means 2 includes a voltage dividing resistor R as a voltage change detection circuit that changes the output voltage 3 according to changes in the charging voltage EB of the battery B2, as shown in FIGS.
6. The capacitor C2 is charged via the diode D2 as a peak voltage holding circuit that holds the voltage at the charge change voltage V3 from R7 and the maximum charge voltage EBmax of the battery B2, and is discharged via the diode D3 when the power is turned off. Charging peak voltage from ■4 and obeah a
x Charge peak voltage V4 by inputting comparison to IC1
A voltage discriminator 3 that changes the output ■5 from rHJ to rLJ when the fully charged a a memory circuit 4 that turns on the silicon-controlled rectifying element SCR1 via the transistor Q3 when the output from the voltage discriminator 3 is inverted to rLJ; resistors R12 to R15; a capacitor C3; and an operational amplifier IC2. and an oscillation drive circuit 5 which blinks a light emitting element such as an LED at a constant cycle and a constant duty ratio determined by a CR time constant when the silicon controlled rectifier SCR1 of the memory circuit 4 is turned off. ing.

Next, the operation of this embodiment will be explained.

The battery charge state detection circuit configured in this way is
When connected to the adapter, a charging voltage V1 is applied between the terminals T1 and T2 to start charging the battery B2, and a switching means 2 based on the output from the voltage detector 1 when the charging voltage 1 is applied. When the oscillation drive circuit 5 is turned on, the oscillation drive circuit 5 is activated, and at the beginning of charging, the voltage V4 of the capacitor C2 is lower than the voltage v3 of the voltage dividing resistors R6 and R7 by the forward voltage force of the diode D2, and the output of the voltage discriminator 3. is rHJ, and both the transistor Q3 and the silicon-controlled rectifier 5CR1 are off, so the LED blinks at C according to the cycle and duty ratio of the oscillation drive circuit 5, indicating that the battery B2 is not fully charged. Display something.

In this way, as charging progresses, the charging voltage of battery B2 gradually increases, and the nickel-cadmium battery 8
As shown in Fig. 4, the charging characteristics of No. 2 are as follows: After the charging voltage was temporarily raised to the highest EBm8X before charging was completed,
The voltage from the voltage dividing resistors R6 and R7 drops in accordance with the voltage EBsat in this fully charged state, but the capacitor C
2 voltage is prevented from discharging by the diode D2, and the input impedance Zi of the operational amplifier IC1 is as high as several 100 MΩ, so the peak voltage corresponding to the highest voltage EBmax is maintained. V4 becomes higher than the non-inverting input voltage V3, and the output of the voltage discriminator 3 becomes r.
In order to avoid turning on the silicon-controlled rectifying element 5CRI together with the transistor Q3, the 5CR
The anode potential V7 of I is pulled to O■, no current flows through the LED, and the LED goes out, indicating that the battery B2 is in a fully charged state.

When you handle the AC adapter at point 14 in Figure 5, when you know that charging is finished when this LED goes out, transistor Q1 loses its base potential and turns off, and transistor Q2 also loses its base current path and turns off, causing switching. The output voltage V2 from the means 2 also becomes ○V, the charge of the capacitor C2 is discharged through the diode D3, and the AC adapter is connected to the terminals Tl and T2 while the charging voltage of the battery B2 has dropped due to the use of the battery B2. By connecting, the operation is repeated again.

Note that the silicon-controlled rectifying element SCR can be replaced with a programmable unijunction transistor PUT, and each of the circuits 1 to 5 can also be any circuit corresponding to the display format.

(Effects of the Invention) The present invention detects a change point caused by a temporary increase in the charging voltage of a nickel-cadmium battery at the completion of a full charge, and changes the lighting state of a light emitting element from one of on and off to the other. This makes it easy to visually confirm whether a nickel-cadmium battery is being charged or when charging is complete, as well as to determine whether undercharging or overcharging improves the operability of the battery-powered motor device, reduces unnecessary charging power, and improves battery life. It is possible to effectively prevent a decrease in service life.

[Brief explanation of drawings]

Fig. 1 is an electrical circuit diagram of a conventional embodiment, Fig. 2 is an electrical circuit diagram of an embodiment of the present invention, Fig. 3 is a block diagram thereof, and Fig. 4 shows changes in charging voltage of the nickel-cadmium battery. The characteristic diagram shown in FIG. 5 is its operating characteristic diagram. 1... Voltage detector 2... Switching means 3
...Voltage discriminator 4...Memory circuit 5...Oscillation drive circuit LED...Light emitting element B2...Nickel cadmium battery Figure 1

Claims (1)

[Claims] A voltage change detection circuit that changes the output voltage according to changes in the charging voltage of the nickel-cadmium battery, a peak voltage holding circuit that holds the voltage at the maximum charging voltage of the nickel-cadmium battery, and a charging change from the voltage change detection circuit. a voltage discriminator that compares the voltage with the charge peak voltage from the peak voltage holding circuit and changes the output when the charge peak voltage becomes higher than the charge change voltage; and a voltage discriminator that changes the output when the charge peak voltage becomes higher than the charge change voltage. and a charge state display circuit that changes a lighting state from one of on and off to the other according to an output from the voltage discriminator when the battery is charged.