JPS5821799B2 - charge/discharge circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charging circuit for a flash discharge lamp, and more particularly to a circuit that can obtain an excitation current with a long duration even if the connection length of a unit circuit is shortened.

Conventionally, a circuit using a capacitor C and a coil L has been used as a circuit for sustaining a relatively high current in an excitation circuit for a high-output laser such as a pulse laser.

As a circuit consisting of this capacitor and a coil, a circuit consisting of one capacitor and a coil each, and a circuit consisting of multiple stages of capacitors and coils having the same capacitance and inductance have been used.

However, in the former circuit consisting of a single coil and a capacitor, only a chevron-shaped current waveform is obtained, and a high current value cannot be sustained for a long time.

On the other hand, a circuit with multiple stages of capacitors and coils with the same amount of capacitance and inductance can maintain a high current value, but if you want to shorten the rise time compared to the pulse width, you need to increase the number of stages. There was a drawback that it had to be.

The present invention was developed in order to eliminate the drawbacks of the conventional charging/discharging circuits described above, and by inserting a plurality of unit circuits with equal line impedance between the power supply and the excitation lamp, the rise time is short and the current is high. The purpose is to provide a circuit that can obtain waves.

The details of the present invention will be explained below with reference to the illustrated embodiments.

FIG. 1 is a circuit diagram of a case in which the present invention is applied to a pulsed laser oscillation circuit, and FIG. 2 is a waveform diagram showing current values over time in the same actual case.

In general, if the impedance Z of a unit circuit consisting of a capacitor with a capacity C and a coil with an inductance L is equal to the equivalent impedance of the discharge lamps connected in a row, and they are connected in multiple stages, the current waveform flowing through the discharge lamps will be as shown in Figure 2. As shown, it becomes a square wave.

The width τW is τW=2, where n is the number of stages of the unit circuit.
Indicated by nZC.

In FIG. 1, a delay circuit 2 is inserted between an excitation power source (not shown) and a discharge lamp 1 lit by this power source.

This delay circuit 2 includes a coil Lo and a capacitor C8.
are a pair of unit circuits 3, and these coils and capacitors having the same inductance and capacity are connected in multiple stages, and a coil L1 . ......, L5, capacitor C1
, C2, . . . , C6 are connected.

The custom-made impedance of these delay circuits 2 is the equivalent impedance of the discharge lamp 1! Make them almost equal.

In order to obtain a waveform in which the ratio of the pulse width τW to the pulse rise time τr is τW:τr=100:1, conventionally, it has been necessary to connect approximately 56 stages of unit circuits.

However, in this method, excitation. Ten stages of unit circuits are connected to the power supply side, and the pulse width is set to 90% of the desired pulse width with these circuits.

Then, a coil and a capacitor whose inductance and capacitance are successively reduced at the same rate are connected closer to the discharge lamp 1, and at the stage where they are connected to the discharge lamp 1, τW becomes.

Make it 100.

Here, if the ratio of reducing the inductance and capacitance of the coil and capacitor is 50%, the fluctuation ratio of the current flowing through the discharge lamp 1 will be around 30%.

If the reduction ratio is set to 20%, it will change from before to after by 5%.

In discharge lamps used for welding and drilling with laser light, this current change rate of about 10% is acceptable without affecting the lighting of the discharge lamp.

In other words, the reduction ratio between inductance and capacitance is 20%.
It is sufficient.

In this way, a unit circuit that requires 56 stages of connection in the conventional system can achieve a sufficient effect with 15 stages of connection according to the present system.

FIG. 3 is a circuit diagram of another actual case, and FIG. 4 is a waveform diagram showing current values over time in the same example.

It is.

□In the figure, two excitation power supplies (not shown)
, two types of unit circuits having different inductances and capacitances are connected in n1 and n2 stages, respectively, and are integrally connected in parallel to the discharge lamp 1 side via rectifying elements 4 and 5.

The line impedance formed by these unit circuits also discharges as in the previous leprosy case.

Make it equal to the equivalent impedance of lamp 1.

In this actual case, when the charging voltage due to the line impedance is set to El and E2 and E1=4E2 is satisfied, the discharge current flowing through the discharge lamp 1 at this time is as shown in FIG.

Generally, the peak value of current is approximately proportional to the square of the voltage, so
Each peak value IP1°IF5 becomes IP1=161P2, and each circuit is closed.

By changing C, L, E, and n in this way, pulse trains with different peak values and pulse widths can be obtained.

In this case, as in the above embodiment, it is also possible to connect coils and capacitors whose inductance and capacitance are successively reduced toward the discharge lamp side, thereby reducing the size of the entire circuit.

As described above, in the present invention, the charging circuit is configured with a circuit that has an impedance equal to the equivalent impedance of the discharge lamp, and whose capacitance and inductance are reduced at the same rate. Therefore, a short circuit can handle a current with a long peak value. Now you can get it.

The present invention is not limited to the above embodiments, and can be modified without departing from the gist.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an actual example in which the present invention is applied to a pulsed laser oscillation circuit, Fig. 2 is a waveform diagram showing the current value over time in the same example, and Fig. 3 is a waveform diagram showing the current value over time in the same embodiment. Another embodiment circuit diagram, FIG. 4, is a waveform chart showing current values over time in the same embodiment. 1...discharge lamp, 2...delay circuit.

Claims (1)

[Claims] 1. An excitation power source, a discharge lamp lit by this power source,
A plurality of circuits are inserted between the power supply and the discharge lamp, and the value of each unit cycle LC consisting of capacitance C and inductance L is decreased at the same rate near the terminal end, and the impedance is the equivalent impedance of the discharge lamp. A charging/discharging circuit comprising a delay circuit that is approximately equal to .