JP3285929B2 - Pulse generation circuit for laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser pulse generating circuit used for a metal vapor laser device represented by a copper vapor laser or the like.

[0002]

2. Description of the Related Art FIG. 9 shows, for example, "Copper Vapor Lasers Come of Age".
e of Age) "(Laser Focus Magazine
FIG. 1 is a circuit diagram showing a conventional laser pulse generation circuit used in a copper vapor laser apparatus described on pages 45 to 49 of July 1982), wherein 1 is a high-voltage power supply, and 2 is a high-voltage power supply. 1, a charging reactor connected in series to the charging reactor 2, a charging diode connected in series to the charging reactor 4, a first capacitor connected in series to the charging diode 3, and a first capacitor 4 connected to the charging capacitor 3. A charging resistor connected in parallel, 6 a peaking capacitor connected in parallel with the charging resistor 5, 7 a laser discharge tube connected in parallel with the peaking capacitor 6 and the charging resistor 5,
8 is a first switch connected in parallel to the connection point between the charging diode 3 and the first capacitor 4, 9 is the inductance of the circuit, 10 is the inductance of the laser discharge tube 7,
11 is a resistance of the laser discharge tube 7.

Next, the operation will be described. The first through the charging reactor 2 and the charging diode 3 from the high voltage power supply 1
Is charged with a high voltage. When the first switch 8 is turned on, the energy of the first capacitor 4 is transmitted to the laser discharge tube 7 through the peaking capacitor 6, and a pulse discharge is formed in the laser discharge tube 7 to cause laser oscillation. Since the life of the upper laser level of the copper vapor laser is extremely shorter than the life of the lower level, the steepness of the discharge current supplied to the laser discharge tube 7 is required for efficient laser oscillation. Therefore, the peaking capacitor 6 is inserted so as to improve the rounding of the waveform due to the inductance 9 of the circuit. That is, the energy of the first capacitor 4 is temporarily stored in the peaking capacitor 6 via the inductance 9 of the circuit, and a steep current is supplied from the peaking capacitor 6 to the laser discharge tube 7. As a result, the current i ₁ supplied from the first capacitor 4 becomes two peaks of the current waveform as shown in FIG. 10.

FIG. 10 shows a general current / voltage and laser waveform of a copper vapor laser. The laser beam L is output in the first half of the current i ₂ flowing through the laser discharge tube 7, the discharge current is not completely effective in the use in laser oscillation. This is based on the relationship between the laser upper level and the lower level as described above. The discharge current is determined mainly by the oscillation width of the peaking capacitor 6, the inductance 10 of the laser discharge tube 7, and the resistance 11 of the laser discharge tube 7.

In the conventional laser pulse generating circuit described above, especially when the laser discharge tube 7 becomes large, the inductance 10 of the laser discharge tube 7 becomes large, so that the width of the discharge current is widened and supplied after laser oscillation. Ratio increases. The current supplied after such laser oscillation (hereinafter, referred to as a subsequent current; a hatched portion in FIG. 10) not only does not contribute to laser oscillation, but also increases the number of laser lower levels to lower oscillation efficiency, In addition, since the resistance 11 of the laser discharge tube 7 is reduced more than necessary, the voltage applied to the resistance 11 of the laser discharge tube 7 in the oscillation operation in the next cycle decreases, causing a harm that laser excitation becomes insufficient. . As described above, the conventional laser pulse generation circuit has a problem that the subsequent current after laser oscillation lowers the efficiency of laser oscillation.

In order to improve the above problems and increase the efficiency of the laser, Japanese Patent Application No. 4-14773 proposes a pulse generating circuit for a laser as shown in FIG.
In FIG. 11, reference numeral 12 denotes a second switch, 25 denotes a resistor connected in series to the second switch 12, and this series circuit is connected in parallel to the first capacitor 4.

Next, the operation will be described. The second switch 12 is turned on at time t _x in FIG. 10 after the first switch 8 is turned on.
Conducted in the vicinity. As a result, the voltage energy of the first capacitor 4 is rapidly consumed and attenuated in the loop of the second switch 12 and the resistor 25. As a result, there is no longer any transfer of energy from the first capacitor 4 to the peaking capacitor 6 after t _x . That is, the subsequent current hardly flows through the laser discharge tube 7 after the laser oscillation is completed. With the above configuration, the efficiency of the laser is greatly improved.

[0008]

Since the conventional laser pulse generating circuit is constructed as described above, in the circuit of FIG. 11, the voltage stored in the first capacitor 4 at t _x in FIG. The energy is only consumed by the resistor 25, and the surplus energy is not effectively used.
For this reason, there has been a problem that a drastic improvement in laser efficiency cannot be expected as a whole.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a laser pulse generation circuit that can reuse energy conventionally consumed.

[0010]

According to a first aspect of the present invention, there is provided a laser pulse generating circuit for storing the voltage energy of a first capacitor in a second capacitor through a second switch. The voltage energy of the capacitor is regenerated to the first capacitor via the power converter.

According to a second aspect of the present invention, there is provided a laser pulse generating circuit which stores the voltage energy of a first capacitor in a second capacitor via a second switch, and stores the voltage energy of the second capacitor in power. The power is regenerated to a high-voltage power supply via a converter.

[0012]

SUMMARY OF laser pulse generator in the first aspect of the present invention, by closing the second switch at the t _x, the voltage energy stored in the first capacitor again via the second capacitor Since the energy is regenerated by the first capacitor, energy is not wasted, and a large improvement in the efficiency of the laser device as a whole can be expected.

[0013] The laser pulse generator in the invention of claim 2, by closing the second switch at the t _x, the voltage energy stored in the first capacitor 4, via the second capacitor Since the power is regenerated by the high-voltage power supply 1, energy is not wasted, and a large improvement in the efficiency of the laser device as a whole can be expected.

[0014]

[Embodiment 1] An embodiment of the first aspect of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a high voltage power supply and 2 is a high voltage power supply 1.
Charging reactor connected in series, 3 is charging reactor
2, a charging diode connected in series to 4;
The first capacitor 5 connected in series with the diode 3
A charging resistor connected in parallel to the first capacitor 4;
Is a peaking capacitor connected in parallel with the charging resistor 5.
7 are parallel to the peaking capacitor 6 and the charging resistor 5.
A laser discharge tube connected to the column, 8 is a charging diode 3
High-voltage power supply 1 at the connection point between
The first switch 9 connected in parallel, 9
Wardrobe, 13 second capacitor, 14 denotes a second diode, the second switch connected in series with the second diode 14 12 connected in series with the second capacitor 13, of the A series circuit including two capacitors 13, a second diode 14, and a second switch 12 is connected in parallel to both ends of the first capacitor 4. Fifteen
Is a third diode connected in parallel to the first capacitor 4, 16 is a power converter connected across the second capacitor 13, 17 is an output of the power converter 16 supplied to the first capacitor 4 A fourth diode.

FIG. 2 shows a configuration of the power converter 16, wherein 18 is a third switch connected to the input side, 19 is a resonance reactor connected to the input side, and 20 is a turn ratio of 1: n. The step-up transformers a and b are output terminals of the step-up transformer 20.

FIG. 3 shows the configuration of the high-voltage power supply 1 and 21.
Is a fourth switch, and 22 is a DC power supply.

Next, the operation will be described. 1 and 4
In the timing chart of FIG. 1, first, in the state before t ₀ , the high voltage power supply 1 supplies the high voltage V ₀ to the first capacitor 4.
Is stored. In this state, when the first switch 8 is turned on at t ₀ , the high voltage of the first capacitor 4 passes through the inductance 9 of the circuit and is supplied to the laser discharge tube 7 via the peaking capacitor 6. Since laser oscillation Beyond t ₁ is terminated, to prevent the energy supplied to the laser discharge tube 7 to t ₁ later wasted, thereby turning the second switch 12 at t _1. When the second switch 12 is conductive, the voltage V _x is the first capacitor 4 accumulated in the first capacitor 4 in t _1, the second capacitor 13, a second diode 14, the second switch 12 Discharged in a loop.

Now, the capacitance value of the second capacitor 13 is set to the first value.
If you select a value that is sufficiently larger than the capacitance value of the capacitor 4,
The oscillation of the loop is roughly determined by the inductance 9 of the circuit and the first capacitor 4. At this time, i3 shown in FIG.
Increases in accordance with the above-described oscillation period, and at the same time, charges are gradually accumulated in the second capacitor 13, and the voltage of Vc2 increases. When the current in i3 is at its maximum value, the energy in the first capacitor 4 is transferred substantially to the electromagnetic energy of the circuit, after which i3 returns with the third diode 15 as i4 and the electromagnetic energy in the inductance 9 of the circuit to the second. To the capacitor 13 of FIG. If the third diode 15 is not provided, the oscillation in the loop continues, so that the energy of the first capacitor 4 cannot be smoothly transferred to the second capacitor 13. Next, the operation of transferring the electromagnetic energy to the second capacitor 13 at t2 ends . Then, the energy stored in the second capacitor
Energy is maintained as it is by the second diode 14
Is done.

If the capacitance of the second capacitor 13 is, for example, n ² times the capacitance of the first capacitor 4 (n is the turns ratio of the step-up transformer 20), V _c2 becomes V _x by t _2.
/ Voltage n ² is stored. After t ₂ , the second diode 14 prevents the voltage of the second capacitor 13 from flowing backward. In this way, unlike the conventional method in which the surplus energy of the first capacitor 4 at time t ₁ is consumed by the resistor, the excess energy is temporarily stored in the second capacitor 13. Next, when t ₃ is reached after a certain period of time, FIG.
Is turned on. A of the power converter 16
The terminal is connected to one end of the first capacitor 4 through the fourth diode 17, and the terminal b is connected to the other end of the first capacitor 4. As a result, the second capacitor 13, the resonance reactor 19,
A resonance circuit of the first capacitor 4 is formed. here,
Since the turns ratio of the step-up transformer 20 is 1: n, when the first capacitor 4 is viewed from the second capacitor 13 through the step-up transformer 20, it looks n ² times.

As described above, if the second capacitor 13 is selected to be n ² times the first capacitor 4,
The resonance circuit formed by the capacitor 13, the resonance reactor 19, and the first capacitor 4 has a transfer efficiency of 100%.
Is formed. That is, at t _{4 when} half of the resonance period of the circuit has passed, the voltage V
The energy of _x / n will be completely transferred to the first capacitor 4. At this time, the first capacitor 4 would be charged with a voltage again V _x, will come back again excess energy via a fixed time. Of course, at this time, since the first switch 8 is already in the off state, the voltage of the first capacitor 4 is maintained as it is. Now becomes t _5, since the fourth switch 21 of the high-voltage power supply 1 is turned on, to supply a voltage from the DC power supply 22 to the first capacitor 4, the voltage of the first capacitor 4 is V ₀
Will be charged again. As a result, the state at time t _{0 in} FIG. 4 is reached again, and the same operation as described above is repeated. As described above, in the first embodiment, the surplus energy of the first capacitor 4 at time t ₁ is temporarily stored in the second capacitor 13, the first switch 8 is turned off, and then the first Since it is configured to return to the capacitor 4, it can be reused without simply consuming energy as in the related art.

Embodiment 2 FIG. FIG. 5 shows an embodiment of the second aspect of the present invention, and portions corresponding to those in FIG. 1 are denoted by the same reference numerals. In FIG. 5, reference numeral 23 denotes a power converter connected to both ends of the second capacitor 13, the output of which is returned to the first capacitor through the fourth diode 17.

FIG. 6 shows the high-voltage power supply 1,
Is connected to the fourth switch 21 and the DC power supply 22.
Is connected between. FIG. 7 shows the power converter 23, and 24 is a flyback transformer having a turns ratio of 1: n, and the third switch 18 is connected to the input side.

Next, the operation will be described. 5 and 8
In the timing chart, first, the excess energy of the first capacitor 4 is stored in the second capacitor 13, third switch 18 becomes conductive at t _1. At this time, a voltage is generated on the secondary side of the flyback transformer 24, but the fourth diode 17 prevents the current from flowing. Energy of the second capacitor 13, the flyback transformer 24 is flowing current i ₅ as shown in FIG. 8
Is gradually converted as electromagnetic energy by the excitation inductance on the primary side of the. And the second capacitor 13
Half of the resonance cycle of
All the energy of the capacitor 13 is stored as _I0 in the exciting inductance. At this time, at t ₂ , the third
When the switch 18 is turned off, the electromagnetic energy stored in the exciting inductance is
, And a voltage is supplied to the DC power supply 22 through the fourth diode 17. As a result, the electromagnetic energy supplies a current i ₆ to the DC power supply 22 to regenerate the energy. As described above, the second embodiment
According to the above, the energy stored in the second capacitor 13 is converted by the power converter 23 into the DC power supply 2 in the high-voltage power supply 1.
2, the energy previously consumed by the resistor can be reused, and the surplus energy of the first capacitor 4 is not wasted.

In the first and second embodiments, the power converter 16 has been described as a converter of the capacity transfer type, and the power converter 23 has been described as the flyback type. However, both can be applied to either embodiment. The same effect can be obtained by a conversion method for transmitting other energy.

[0025]

As described above, according to the first aspect of the present invention, the voltage of the first capacitor is stored in the second capacitor through the second switch, and the energy is stored in the second capacitor through the second switch. Since it is configured to return to the first capacitor, the subsequent current flowing through the discharge tube after the laser oscillation can be suppressed, and the energy of the first capacitor that does not contribute to the laser oscillation is not wasted and the next cycle is not wasted. Can be used for part of the voltage stored in the first capacitor at
There is an effect that the laser efficiency as a whole can be greatly improved.

[0026] According to the second aspect of the present invention, the conductive 圧E energy of the first capacitor via a second switch stored in the second capacitor, returned to a high voltage power supply via a power converter which With such a configuration, it is possible to suppress the subsequent current flowing through the discharge tube after the laser oscillation, and to save the energy of the first capacitor that does not contribute to the laser oscillation to the first capacitor in the next cycle without wasting it. Can be used for a part of the voltage stored in the memory, and there is an effect that the laser efficiency as a whole can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment according to the present invention;

FIG. 2 is a circuit diagram illustrating a power converter according to the first embodiment.

FIG. 3 is a circuit diagram illustrating a high-voltage power supply according to the first embodiment.

FIG. 4 is a timing chart showing the operation of the first embodiment.

FIG. 5 is a circuit diagram showing a second embodiment according to the second aspect of the present invention.

FIG. 6 is a circuit diagram illustrating a high-voltage power supply according to a second embodiment.

FIG. 7 is a circuit diagram illustrating a power converter according to a second embodiment.

FIG. 8 is a timing chart showing the operation of the second embodiment.

FIG. 9 is a circuit diagram showing a conventional laser pulse generation circuit.

FIG. 10 is a waveform chart showing the operation of the conventional circuit.

FIG. 11 is a circuit diagram showing another example of a conventional laser pulse generation circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-voltage power supply 4 First capacitor 6 Peaking capacitor 7 Laser discharge tube 8 First switch 12 Second switch 13 Second capacitor 16,23 Power converter

Continued on the front page (72) Inventor Shigeo Sakuguri 8-1-1, Tsukaguchi-Honmachi, Amagasaki-shi Mitsubishi Electric Corporation Central Research Laboratory (58) Fields investigated (Int. Cl. ⁷ , DB name) H03K 3/53 H01L 3/097

Claims (2)

(57) [Claims] 1. A series connection between a high-voltage power supply and a laser discharge tube
Connected to the first condenser and the laser discharge tube in parallel
Between the peaking capacitor and the first capacitor.
A first switch connected in parallel with the high-voltage power supply on the power supply side.
And the first capacitor connected in series with each other.
A second capacitor connected in parallel between the terminals and
After the first switch is closed, the first switch is closed.
A second capacitor for supplying the discharge current of the sensor to the second capacitor.
Switch and the primary side through the third switch
2 between the terminals of the capacitor
The other end of the secondary side connected to the power supply side terminal of the first capacitor
Is connected to the other end of the first capacitor.
And a power converter for returning voltage energy stored in the second capacitor to the first capacitor. 2. A series connection between a high voltage power supply and a laser discharge tube.
Connected to the first condenser and the laser discharge tube in parallel
Between the peaking capacitor and the first capacitor.
A first switch connected in parallel with the high-voltage power supply on the power supply side.
And the first capacitor connected in series with each other.
A second capacitor connected in parallel between the terminals and
After the first switch is closed, the first switch is closed.
A second capacitor for supplying the discharge current of the sensor to the second capacitor.
Switch and the primary side through the third switch
2 between the terminals of the capacitor
Connect to the supply side terminal of the high voltage power supply and ground the other end of the secondary side
A pulse converter having a step-up transformer and a power converter for returning voltage energy stored in the second capacitor to the high-voltage power supply.