JPS5822930B2 - charging circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charging circuit consisting of an adapter incorporating an inverter circuit and a device main body connected to the adapter. When the impark circuit becomes unloaded,
An object of the present invention is to provide a charging circuit that can prevent abnormal oscillation and circuit destruction.

FIG. 2 shows an example of a conventional charging circuit, and the adapter 2 connects the AC side terminal of the diode bridge Re1 to the commercial power supply input terminals A and B, and also connects the DC side terminal of the diode bridge Rel. Connect to inverter circuit 1, and connect the output of this inverter circuit 1 to rectifier diode D.
The adapter 2 is connected to the charging output terminals C and D through the adapter 2, and the power receiving input terminals E and F of the appliance body 3, such as an electric shaver, are connected to the charging output terminals C and D of the adapter 2, respectively. It's Nishide.

The inverter circuit 1 is mainly composed of an inverter transistor Tr and an inverter transformer T1, and the inverter transformer T1 is composed of three windings L1, L2, and L3 that are magnetically coupled to each other, and the first winding L1 is a collector winding. and the second winding L2
is the output winding of the inverter circuit 1, and the third winding L3 is
is connected to the base circuit of the inverter transistor Tr to serve as a feedback winding for oscillation of the inverter circuit 1.

Further, the appliance main body 3 is like an electric razor with a built-in rechargeable battery B as described above, and the blade block 1
When the appliance main body 3 is connected to the adapter 2, which is configured with a drive motor M, a battery B, and a power switch SW, and is connected to a commercial power source with the power switch 8W open, the impark circuit in the adapter 2 When the battery B is charged by the rectified output of 1 and the appliance body 3 is connected to the adapter 2 with the power switch SW closed, the inverter circuit 1
The motor M is directly driven by the rectified output, and the main body of the instrument is operated by an AC drive.

However, in such a conventional example, it is common for a user to remove the appliance body 3 from the adapter 2 while the commercial power input terminals A and B of the adapter 2 are connected to the commercial power supply. However, in such a case, charging output terminals C and D must be opened (
As a result, the impark circuit 1 is driven with its output open.

For this reason, the impark circuit 1 is operated with no load with the output open, which may cause abnormal oscillation or an increase in the primary current, which may result in destruction of the circuit due to heat generation or the like.

The present invention has been provided in view of the above points, and one embodiment of the present invention will be described below in detail with reference to the drawings.1 Figure 1 shows a circuit of an embodiment of the present invention, and shows an inverter transformer. The primary winding L4 of another transformer T2 is inserted and connected in series to the output circuit on the T1 secondary winding hole 1 side, and this transformer T2
The secondary winding of the inverter transformer T1 is connected to the base circuit of the inverter transistor Tr to serve as a feedback winding. The L2 output is rectified by the second diode bridge Re2 and connected to the charging outputs C, D.

In Figure 1, R1 is a fuse resistance, R2 is a surge absorption resistance,
R3 is a bias resistor, R4 is a base resistor, R5 is a spike absorption resistor, R6 is an emitter resistor, R7 is a charging current control resistor, C1 is a smoothing capacitor, C is a speed-up capacitor, and C3 and C4 are capacitors for spike absorption. be.

However, in the embodiment circuit of FIG. 1, when the adapter 2 is connected to the commercial power supply, some current flows through the collector of the inverter transistor Tr, and the inverter transformer Tr
When a voltage is induced in the secondary winding L2 of the adapter 2, the transformer T2
A current flows through the primary winding L4, which induces a voltage in the secondary winding, and a current flows through the base circuit of the inverter transistor Tr.

In this way, the current begins to flow through the base 1 circuit, and the current further increases and flows through the collector circuit of the inverter transistor Tr, and due to the above-mentioned positive feedback operation, the inverter transistor Tr quickly reaches a saturated state. Become.

Once this inverter transistor Tr is saturated and its collector current no longer increases, the inverter transformer T
A voltage is induced in the secondary winding L2 of the transformer T2, and feedback to the base circuit via the secondary winding of the transformer T2 is no longer applied, so the collector current of the inverter transistor T2 begins to decrease. When this collector current starts to decrease, a feedback opposite to that in the case of the booster is applied to the base circuit, and the inverter transistor Tr is suddenly turned off.

In this way, the inverter circuit 1 repeats oscillation and supplies a charging current to the battery B in the appliance body 3. However, when the appliance body 3 is not connected to the adapter 2, the primary No current flows through winding L4, so the second
Since no voltage is induced in the next winding L5 and feedback is applied to the base circuit of the inverter transistor Tr, the inverter circuit 1 does not perform oscillation operation, even if the adapter 2 remains connected to the commercial power supply. , problems such as heat generation due to abnormal oscillation do not occur.

Note that in the above circuit operation, the inverter transistor T
Although the oscillation operation due to the saturation of r has been described, a similar oscillation operation can also be obtained using the magnetic saturation of the impark transformer T1.

As described above, the present invention involves inserting and connecting a transformer in series to the secondary winding of an oscillation transformer of an impark circuit, and connecting the secondary winding of this transformer to a feedback winding for positive feedback connected to the base of a transistor. This prevents the inverter circuit inside the adapter from oscillating under no-load conditions when the adapter is not connected to the main unit and the adapter is connected to a commercial power source. Therefore, there is no inconvenience such as abnormal oscillation, and there is no risk of abnormal heating of the inverter circuit or circuit destruction due to abnormal increase in the primary current of the inverter circuit, and it can be used safely. It is.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, and Fig. 2 is a circuit diagram of a conventional example, where 1 is an inverter circuit, 2 is an adapter, 3 is the device body, L, - L4 are windings, and Tr is a transistor. ,R
el is a rectifier circuit, T1. T2 is a transformer and T5 is part 2
This is the next winding.

Claims (1)

[Claims] 1 Feedback in which the primary winding of an oscillation transformer is connected to the output of a rectifier circuit connected to an AC power source via the collector-emitter of a transistor, and a portion of the oscillation output of this oscillation transformer is positively fed back to the base of the transistor. In a charging circuit that includes an adapter having an impark circuit including a winding, and a device body connected to the adapter to receive power from the rectified output of the inverter circuit, the impark circuit is connected in series to the secondary winding of the oscillation transformer of the inverter circuit. A charging circuit 6 characterized in that a transformer is inserted and connected to the transformer, and the secondary winding of the transformer serves as the feedback winding for the positive feedback.