JPH073804Y2 - Rechargeable battery charger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field of the invention) The present invention relates to a charging device for a rechargeable battery, and when charging is completed, the load of an output coil that supplies a charging stream is suddenly dropped,
The inverter is designed to prevent abnormal oscillation.

(Background of the Invention) A charging device for a rechargeable battery, which is often used as a power source unit of a small electric device such as a portable voice reproducing device, is generally composed of an inverter incorporating an oscillating transistor in order to reduce its size and weight. The rechargeable battery is charged by the induced current in the output coil of the inverter. However, the conventional charging device of this type has a problem that the load of the output coil suddenly drops at the same time as the charging is completed, so that the inverter is oscillated abnormally and the device is apt to malfunction.

(Object of the Invention) The present invention provides a device for preventing the inverter from abnormally oscillating due to a sudden drop in the load of the output coil of the inverter that supplies the rechargeable battery with a continuous charge when the charging of the rechargeable battery is completed. The purpose is to do.

(Outline of the Invention) In the present invention, a rechargeable battery E is connected to an output coil N3 of an inverter 3 composed of an oscillating transistor Tr1, and the output coil N3 is connected to the output coil N3.
In the charging device configured to charge the rechargeable battery E with the induced current of the above, the detection unit B for the terminal voltage of the rechargeable battery E and the driving coil N4 serving as a drive power source for the detection unit B are independent of the output coil N3. The load section GN is connected to the output coil N3, and the load section GN is driven by the output coil N3 according to the charge detection signal of the detection section B. With this configuration, when the charging of the rechargeable battery is completed, the load portion of the output coil is driven to prevent the load of the output coil from suddenly dropping, thereby preventing abnormal oscillation of the inverter. Is.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a charging circuit for the rechargeable battery. The charging circuit detects the terminal voltage of the rechargeable battery E and drives the charging unit A by detecting the terminal voltage of the rechargeable battery E. It comprises a detection unit B for stopping the. Reference numeral 1 denotes a power plug, which has a filter function by a protection capacitor C1 and protection resistors R1 and R2, and is connected to an inverter 3 via a bridge rectifier 2 and a noise removal filter C2. The inverter 3 is composed of an oscillation transistor Tr1, a bias resistor R3, a primary coil N1, a feedback coil N2, etc.
When the power plug 1 is connected to the power source, the transistor Tr1 becomes conductive, the inverter 3 oscillates, and the induced current IA of the output coil N3 wound around the same core as the coils N1 and N2 causes
A rechargeable battery E such as a nickel-cadmium battery connected to this is charged. 7 is a fuse, D1 and D2 are transistors
Voltage regulating diode to prevent abnormal oscillation of Tr1,
C3 is a starting capacitor, D3 is a discharge loop diode for the capacitor C3, C4 and R4 are protective capacitors and resistors, D6 is a rectifying diode, and C5 is a smoothing capacitor.

A1 is an operational amplifier, one input part of which is a positive electrode of the rechargeable battery E via a smoothing capacitor C6, and the other input part is a first reference voltage part composed of diodes D4, D5 and a variable resistor R5. Connected to 5. A2 is a second operational amplifier, one input portion of which is connected to the second reference voltage portion 6 composed of the resistor R6, and the other input portion of which is connected to the output portion of the first operational amplifier A1. . ZD is a zener diode for constant voltage, C9 is a smoothing capacitor, N4 is an operational amplifier A
It is a driving coil for A1 and A2.

Reference numeral 8 is a photocoupler for connecting the charging unit A and the detection unit B, which is composed of a light emitting element 8a and a light receiving element 8b. When the output of the operational amplifier A2 is L, the light emitting element 8a emits light and the light receiving element 8b becomes conductive, The transistor Tr2 connected to the light receiving element 8b becomes conductive, the transistor Tr1 becomes conductive, and the collector current Ia flows, the inverter 3 oscillates, and the rechargeable battery E is charged.
When the output of operational amplifier A2 changes from L to H, the light emitting element
8a is turned off and the transistor Tr2 is cut off. After that, the collector current Ib of the transistor Tr1 slightly flows through the large resistor R7, the oscillation of the inverter 3 is weakened, and the charging current to the rechargeable battery E is attenuated. Then, the auxiliary charging state is established. C7 is a start capacitor at power-on, R8 is a resistor for detection voltage hysteresis, C8, C9
Are capacitors and resistors for improving detection accuracy.

RE is a red light emitting element for charging display, GN is a green light emitting element for charging end display as a load section, and the light emitting element RE is by connecting the base of the switching element Tr3 to the output section of the operational amplifier A2, The light emitting element GN is controlled by connecting the base of the switching element Tr4 to the output part of the operational amplifier A1. When charging of the rechargeable battery E is completed and the output of the operational amplifier A1 changes from H to L, the base current of the switching element Tr4 flows by the charging detection signal, the switching element Tr4 becomes conductive, and the light emitting element GN.
Is driven by the output coil N3 to emit light. Dn is a constant voltage circuit composed of a plurality of diodes connected to the rechargeable battery E, which prevents the light emitting elements RE, Gn from being too bright without the rechargeable battery E, and is not always necessary. .

This device is configured as described above, and when the power plug 1 is connected to the power source, the inverter 3 oscillates and the output coil N3
An induced current IA is generated in the rechargeable battery E and the rechargeable battery E is charged. At this time, the output of the operational amplifier A1 is H and the output of the operational amplifier A2 is L. In this state, the light emitting element 8a is lit and the light receiving element 8b is conducting, and the base current flows through the transistor Tr2 to conduct the transistor Tr2. Tr1 remains conductive. In this state, the switching element Tr3 is turned on and the light emitting element RE is turned on to indicate that charging is in progress. When the charging of the rechargeable battery E progresses and its terminal voltage becomes higher than the voltage of the reference voltage unit 5, the output of the operational amplifier A1 changes from H to L, and the output of the operational amplifier A2 changes from L to H. Then the light receiving element
8a goes off, the light receiving element 8b stops driving, and the transistor
Tr2 is cut off, and the rechargeable battery E is charged in a supplementary charging state. When charging is completed in this way, the switching element Tr3 is cut off, the light emitting element RE is turned off, and the switching element Tr4 is turned on to emit the light emitting element GN.
Lights up in green to indicate that charging is completed, but when charging of the rechargeable battery E is completed by driving the load part such as the light emitting element GN to the output coil N3 at the same time as the completion of charging in this way. Moreover, it is possible to prevent the load of the output coil N3 from suddenly dropping and causing the inverter 3 to abnormally oscillate.

(Effect of the Invention) As described above, the present invention is based on the oscillation transistor Tr1.
In the charging device in which the rechargeable battery E is connected to the output coil N3 of the inverter 3 and the rechargeable battery E is charged by the induced current of the output coil N3, A drive coil N4 serving as a drive power source for the detection unit B is provided independently of the output coil N3, a load unit GN is connected to the output coil N3, and the load unit GN is detected by the charge detection signal of the detection unit B. Is driven by the output coil N3, so that when the charging of the rechargeable battery E is finished, the load of the output coil N3 suddenly drops and the inverter 3 abnormally oscillates to prevent the device from malfunctioning. be able to.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. 1 is a charging circuit diagram. B: Detection section E: Rechargeable battery GN: Load section N3: Output coil N4: Driving coil Tr1: Oscillation transistor 3: Inverter

Claims (1)

[Scope of utility model registration request] 1. A rechargeable battery E is connected to an output coil N3 of an inverter 3 composed of an oscillating transistor Tr1, and the output coil is connected to the output coil N3.
In a charging device configured to charge the rechargeable battery E by an induction current of N3, a detection unit B for the terminal voltage of the rechargeable battery E and a driving coil N4 serving as a driving power source for the detection unit B are connected to the output coil N3. Provided independently, load part GN to output coil N3 above
And a load detection signal from the detection unit B, and the load unit GN is driven by the output coil N3.