JPS58393Y2 - Biden Atsushi Liyu Cairo - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a capacitor charging circuit, particularly a discharging capacitor charging circuit used in strobes and the like.

Conventionally, a capacitor charging circuit using a voltage doubler rectifier circuit has a protective resistor R between AC input terminals 1 and 2, as shown in Figure 1.
1, a pumping capacitor C1, a diode DIl, and a load capacitor CL are connected in series, and a diode DI2 is connected between a connection point between the pumping capacitor C1 and the diode DII and a terminal 2.

Incidentally, since alternating current is applied to the pumping capacitor C1, it is preferable to use a non-polar capacitor in order to prevent its destruction.

However, since flash devices such as strobes are particularly required to be miniaturized, polar electrolytic capacitors are used as pumping capacitors CI.

Even if a polar electrolytic capacitor is used, under normal conditions, the reverse voltage applied to it during operation will be extremely short-lived and will have little effect, but if capacitor CL is destroyed and short-circuited, , electrolytic capacitors may be destroyed if reverse voltage is applied for a long period of time.

As is well known, an electrolytic capacitor has an electrolytic solution inside it, so if it is destroyed, this electrolytic solution will scatter, damaging other electrical parts and the flash device itself made up of these parts.

Furthermore, due to the nature of the purpose of flash devices, which are often used for photography and copying, it is necessary to charge the capacitor cL quickly, but with the conventional capacitor charging circuit shown in Figure 1, Due to the pumping capacitor C1, its charging speed was limited.

The object of the present invention is to provide a capacitor charging circuit that eliminates the above-mentioned drawbacks.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, the same parts as in FIG. 1 are indicated by the same symbols.

1 and 2 are AC input terminals to which an AC voltage is applied.

A protective resistor R, a pumping capacitor C2, a diode D1 . and a capacitor CL are connected in series.

In parallel with pumping capacitor C2 and capacitor C
A bypass diode DI3 is connected to L in the direction in which current flows.

Further, a diode DI2 is connected between the connection point between the pumping capacitor C2 and the diode DII and the AC input terminal 2.

That is, the AC voltage applied to each AC input terminal 1 and 2 is boosted and rectified to double the voltage by the pumping capacitor C2, the diodes DI, and DI2, and the capacitor CL is charged.

At this time, the alternating current voltage is half-wave rectified by the bypass diode DI3, so when the capacitor cL has a large capacity, such as one used in a strobe, the charging time is significantly shortened (by more than 20%).

If the capacitor cL is destroyed and short-circuited,
Since the current flows through the protective resistor R, the bypass diode DI3, and the diode DII, no reverse current flows to the pumping capacitor C2, so that it will not be destroyed.

Further, due to the short circuit of the capacitor cL, a large current flows through the protective resistor R, which is destroyed and functions as a fuse, with almost no effect on other electrical components.

As described above, in the present invention, since the reverse current flowing through the pumping capacitor can be shunted to the bypass diode, destruction of the pumping capacitor can be prevented, and damage to other components can also be prevented.

Further, since the AC voltage can be half-wave rectified by the bypass diode, the charging time of the capacitor can be significantly shortened.

[Brief explanation of the drawing]

FIG. 1 shows a conventional voltage doubler rectifier circuit diagram, and FIG. 2 shows a voltage doubler rectifier circuit diagram of the present invention. R...Protection resistor, C1...Pumping capacitor, CL...Capacitor, Dll,
DI2...Diode, DI3...
Bypass diode.

Claims (1)

[Claims for Utility Model Registration] A polar pumping capacitor C2, a forward rectifier diode D11, and a load capacitor CL are connected in series, and a rectifier diode DII and a load capacitor CI. A diode DI2 is connected in parallel to the series circuit of the rectifying diode DII so that its cathode is on the anode side of the rectifying diode DII.
In this circuit, a bias diode DI3 is connected in parallel to the pumping capacitor C2 in the direction in which current flows through the load capacitor CL, and the cathode side of the bypass diode DI3 is connected to the positive electrode side of the polar pumping capacitor C2. A capacitor charging circuit characterized by being connected to.