JPS6227002Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a battery charging device, and is intended to more reliably turn off a charging indicator light after the charging of the battery to be charged is completed.

Conventionally, when a battery to be charged is rapidly charged with a large current and supplementary charged with a small current after battery charging is completed, a detection element is provided in the charging path of the battery to detect the magnitude of the charging current, and the detection element detects the magnitude of the charging current. A charging indicator light was provided at the collector of the detection transistor, to which the voltage across the battery was applied between the base and emitter. In this conventional device, since the charging current decreases after charging is completed, the brightness of the charging indicator light decreases, and when used in a bright place, the charging indicator light appears to be off, making it an appropriate display device. However, when using the device in a dark place, the charging indicator light remains on even during supplementary charging, so the user must recognize the charging completion state due to the decrease in brightness, which has the drawback of making it difficult to recognize.

The present invention has been devised in view of these points, and one embodiment of the present invention will be described below with reference to the drawings.
X is a charger and Y is a battery pack. Charger X has a step-down transformer Tr, and its primary coil N ₁ has connection ends P ₀ and P ₀ of commercial power supply E. step down transformer
Both ends of the secondary coil N ₂ of the Tr are connected to the positive line 1 via diodes D ₀ and D ₀ , and the secondary coil
The middle tap of N ₂ is connected to negative line 2. The positive and negative lines 1 and 2 constitute a charging path 3 for the battery B, and a smoothing capacitor _C1 is inserted between the positive and negative lines. The charger X has first to third terminals P ₁ to P ₃ , the positive line 1 is connected to the first terminal P ₁ and the negative line 2 with the gated thyristor S is connected to the third terminal P ₃ . A first diode is connected between the second terminal P ₂ and the negative line 2 on the cathode side of the thyristor S.
A series circuit of D ₁ , resistor R ₁ , second diode D ₂ and first Zener diode Z ₁ is connected, and resistors R ₂ and R ₃ are connected in parallel with the series circuit of second diode D ₂ and first Zener diode Z ₁ . series circuits are connected in parallel. A capacitor C ₂ is connected in parallel to the resistor R ₂ ,
A resistor R ₃ is connected between the gate and cathode of the thyristor S.

The charger X also includes an indicator light circuit 4 between one end of the secondary coil N ₂ and the negative line 2. The circuit includes a diode D 3 between one end of the secondary coil N ₂ and the negative line ₂ on the cathode side of the thyristor S
A series circuit of a resistor _R4 and a second Zener diode _Z2 is connected, and a detection transistor Q for detecting a voltage change of the first Zener diode _Z1 , a resistor _R5 , and a charging indicator are connected across the second Zener diode. It is constructed by connecting a series circuit of light emitting diodes L as a light through the anode and cathode of a thyristor S, and the base of the detection transistor Q is connected to a second diode _D2 and a first zener through a resistor _R6 . Connected to the connection point between the diodes Z ₁ .

Next, the battery pack Y comprises a series circuit of a rechargeable battery B and a thermostat T which opens in response to the thermal effect of the battery B. Both ends and the midpoint of the series circuit are connected to the fourth through sixth terminals _P4 through _P6 of the battery pack Y.

In the above configuration, each terminal P ₄ of battery pack Y
By connecting the terminals P ₆ to the corresponding terminals P ₁ to _{P 3} of the charger X, charging of the battery B starts. That is, since the battery temperature is low at the start of charging, the thermostat T is closed. On the other hand, when charging starts, the capacitor
A current flows into _C2 , and the voltage across resistor _R3 due to this current becomes a gate signal for thyristor S, causing the thyristor to fire and conduct. Therefore, battery B is charged via thermostat T and thyristor S. In this case, the voltage of the first Zener diode _Z1 is smaller than both the step-down voltage of the thermostat T and the thyristor S, and is smaller than the Zener voltage of the second Zener diode _Z2 , so the detection transistor Q
detects this state and becomes conductive. Therefore, the light emitting diode L lights up to indicate that charging is in progress.

As charging progresses in this manner and battery B approaches a fully charged state, the battery temperature rises. When the battery temperature reaches a predetermined temperature, a thermostat T thermally coupled to battery B detects this predetermined temperature and opens. As a result, no current flows through the thyristor S, so the thyristor is cut off. In this case, the light emitting diode L is turned off by shutting off the thyristor S, indicating that the battery is fully charged.

After charging is completed, the battery temperature drops and the thermostat T closes again, but the charging current flows into capacitor _C2 mainly only at the beginning of charging, and by the time the battery temperature drops after charging is completed, the thermostat T closes again.
That charging current does not flow into _C2 . Therefore, the thyristor S will not fire again.

Further, after charging, the voltage of the first Zener diode _Z1 increases due to the interruption of the thyristor S. That is, the Zener voltage of the second Zener diode _Z2 and the first
Since the voltage difference across the Zener diode _Z1 becomes less than the threshold between the base and emitter of the detection transistor Q, the detection transistor is also cut off. This means that when there is no detection transistor Q, when the thermostat T is closed after charging is completed, the light emitting diode L,
thermostat T, diode D ₁ and resistor R ₁ ,
This eliminates the possibility that the light emitting diode L will light up due to current flowing through the circuit of R ₂ and R ₃ .

As described above, according to the present invention, the charging indicator light can be reliably turned off after charging is completed, and unlike conventional devices that indicate charging completion by decreasing the brightness of the charging indicator light, it is possible to turn off the charging indicator light in a dark place. It becomes easier to confirm that charging is complete.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram showing an embodiment of the charging device according to the present invention. B...Battery, 3...Charging path, T...Thermostat, S...Thyristor, 4...Indicator light circuit.

Claims (1)

[Claims for Utility Model Registration] (1) The positive electrode side of a battery to be charged is connected to one end of the secondary coil of a transformer, and a thermostat and a thyristor are connected in series to the negative electrode side of the battery to be charged. In a battery charging device in which a starting capacitor is connected between the gate of a thyristor and the negative electrode of the battery to be charged, a transistor and a light emitting diode are connected between one end of the secondary coil of the transformer and the anode of the thyristor. A first bias element is inserted between the base of the transistor and the cathode of the thyristor, and a second bias element is connected between the emitter of the transistor and the cathode of the thyristor. A battery charging device characterized by: (2) The battery charging device according to claim 1, wherein the first and second bias elements are different Zener diodes.