JP2720826B2 - Ion laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion laser device and, more particularly, to suppressing a high voltage of a trigger pulse applied at the start of discharge of a laser tube from flowing to a power supply side to prevent a power supply circuit from being damaged. About.

[0002]

2. Description of the Related Art An ion laser tube is a discharge tube usually having an anode and a cathode. The ion laser tube generates an arc discharge using an internally charged gas as a medium, and uses the energy to excite the internally charged gas to generate laser oscillation. . In the case of arc discharge such as welding, it is usually possible to start the discharge by reducing the distance between the electrodes and then slightly increasing the applied voltage, but in a laser tube, the distance between the electrodes is constant and the impedance is low. , The discharge cannot be started simply by increasing the voltage of the anode. Therefore, a high voltage is applied, a glow discharge is once generated, and the discharge current is gradually increased, thereby shifting to arc discharge.

As described above, the ion laser tube starts discharge by applying a high voltage serving as a trigger to start the discharge. As the trigger voltage, a DC high voltage or a high frequency high voltage is applied, but a high voltage discharge tube such as a spark gap is used due to the effect of the trigger and the cost and volume of the circuit for generating the high voltage. In general, a high-frequency type trigger is adopted.

However, in the case of a high-frequency type trigger, since the trigger is applied to the anode potential of the laser tube, the trigger is applied to the anode of the laser tube and, at the same time, flows out to the power supply side. To configure the power supply to withstand this high voltage is to increase the withstand voltage of the parts, so that only the main parts become very large, and not all parts have high withstand voltage. However, it is necessary to use a partially insulated circuit, which complicates the design of the power supply, and makes the circuit completely impractical. Therefore, it is necessary to suppress the return to the power supply side for protection of the power supply side, and usually a choke coil is used.
This choke coil requires a large inductance for its effect, and the discharge current is large.
A large current capacity is required, and there is a disadvantage that the volume is increased.

[0005] For example, a conventional ion laser apparatus is shown in FIG.
, A rectifier circuit 2 for rectifying an AC input, a large-capacity electrolytic capacitor 3 for smoothing the output of the rectifier circuit 2,
A choke coil 4 for suppressing return of a trigger applied to the laser tube 7 to the power supply side; a spark gap 6 for applying a trigger to the laser tube; a spark gap driving circuit 5 for driving the spark gap 6; A filament transformer 8 for heating, a power transistor 10 for controlling a discharge current, and a power transistor 10
And a power transistor driving circuit 9 for driving the
The return of the trigger applied to the laser tube to the power supply side is suppressed by the choke coil 4.
However, there is a problem that an inductor having a large inductance and a large current capacity must be used.

It is also conceivable to use a high-voltage diode to suppress the return of the trigger. However, a high-current diode is required as a high-voltage diode for an ion laser, which is expensive and bulky. In addition, since measures for insulation are required, cooling of the diode is also required, and it is disadvantageous in terms of volume, there is a problem in terms of practicality.

[0007]

In this conventional ion laser apparatus, a choke coil is used to suppress the return of the trigger for starting the discharge of the laser tube to the power supply side. It is necessary to use a large capacity choke coil, and there is a certain limit to recent demands for miniaturization and the like, and the present invention reduces the size of a choke coil having the largest volume in a trigger circuit. It is intended to meet the demand for miniaturization.

[0008]

An ion laser device according to the present invention comprises a rectifier circuit for rectifying AC power, a large-capacity capacitor for smoothing its output, and a discharge current flowing through an anode and a cathode of a laser tube. A power transistor for controlling, a driving circuit for driving the power transistor, a filament transformer for heating a cathode of the laser tube, a spark gap for applying a trigger pulse for starting discharge of the laser tube, and a spark gap. In the ion laser device having a spark gap driving circuit for driving the trigger, a trigger for starting discharge is prevented by a choke transformer for preventing return to the power supply side, and a trigger is applied to the primary winding of the choke transformer with respect to the polarity of the trigger voltage. Between the time immediately before the voltage is applied and the time the discharge starts. It has a transistor for controlling the current supplied to the polarity to the primary winding so as to excite within a range not magnetically saturated, a zener diode for driving the transistor, and a resistor.

[0009]

The effect of the choke transformer is that the choke coil operates in the first and fourth quadrants in the BH characteristic (B: magnetic flux density, H: magnetizing force) shown in FIG. The choke transformer operates in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant as a whole, and suppresses the trigger by increasing the current of the primary winding within a range where the transformer is not saturated. Can be further increased, and the volume of the iron core of the choke transformer can be reduced.

[0010]

Next, the present invention will be described with reference to the drawings. FIG.
FIG. 2 is a circuit diagram of one embodiment of the present invention. 1 is an AC power supply,
2 is a rectifier circuit, 3 is a large capacity capacitor, 5 is a spark gap drive circuit, 6 is a spark gap, 7 is a laser tube, 8 is a filament transformer, 9 is a power transistor drive circuit, 10 is a power transistor, 20 is a choke transformer, 21 is a Zener diode, 22 and 23 are resistors, and 24 is a transistor.

An AC power supply 1 is rectified by a rectifier circuit 2 and smoothed by a large-capacity capacitor 3 to produce a DC output. This part may be a DC voltage source. The DC output is supplied to the anode of the laser tube 7 through the secondary winding of the choke transformer 20, and after the discharge starts, the filament transformer 8
Then, it passes through the cathode of the laser tube 7 heated by the above, enters the secondary winding of the filament transformer, and returns to the minus side of the DC output source through the power transistor 10 from the midpoint tap. The power transistor 10 is driven by the drive circuit 9 and controls a discharge current based on a feedback signal or the like. In order to start the discharge, the high voltage generated by the spark gap driving circuit 5 is supplied to the anode of the laser tube 7 through the spark gap 6 as a high frequency high voltage trigger.

Here, at the start of the discharge of the laser tube, AC power is supplied, and the DC output voltage generated by the rectifier circuit 2 and the large-capacity capacitor 3 increases.
When the voltage exceeds the normal laser tube discharge voltage and reaches a voltage at which laser tube discharge can be started, the Zener diode 21 breaks down and also flows through the resistor 22, so that the base voltage of the transistor 24 increases and the transistor 24 becomes conductive. Thereby, the resistance 23 is connected to the primary winding of the choke transformer 20.
The current limited by the current flows. The resistor 23 is set so that this current excites the choke transformer 20 within a range that does not cause the choke transformer 20 to be magnetically saturated. The polarity is set so that the polarity of the trigger voltage applied in the gap 6 is reversed.

Therefore, at the timing when the trigger is applied, the choke transformer 20 is excited in the opposite polarity to the trigger voltage. Even if the trigger is applied, the choke transformer 20 suppresses the return to the power supply side. You. When a trigger is applied and the laser tube starts discharging, a large current flows through the laser tube 7 and the voltage of the large-capacity capacitor 3 decreases, and becomes lower than the breakdown voltage of the Zener diode. And the exciting current to the primary winding of the choke transformer 20 stops,
In the choke transformer 20, only a normal discharge current flows through the secondary winding.

[0014]

As described above, in order to suppress the return of the trigger voltage applied to the laser tube to the power supply side at the start of the discharge, the choke transformer is used, and the primary winding is suppressed by the secondary winding. By supplying a current so as to excite the trigger voltage to the opposite polarity within a range in which the choke transformer does not saturate, the trigger voltage can be reliably suppressed and the choke transformer can be downsized, so that the device can be downsized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a diagram showing B (magnetic flux density) -H (magnetizing force) characteristics of an iron core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Large capacity capacitor 4 Choke coil 5 Spark gap drive circuit 6 Spark gap 7 Laser tube 8 Filament transformer 9 Power transistor drive circuit 10 Power transistor 20 Choke transformer 21 Zener diode 22, 23 Resistance 24 transistor

Claims (1)

(57) [Claims] A rectifier circuit for rectifying AC power, a large-capacity capacitor for smoothing its output, and an anode for a laser tube.
To control the discharge current flowing through the cathode and cathode
A transistor, a driving circuit for driving the power transistor, a filament transformer for heating the cathode of the laser tube, a spark gap for applying a trigger pulse for starting discharge of the laser tube, and driving the spark gap In an ion laser device having a spark gap drive circuit, a trigger for starting a discharge is prevented by a choke transformer for preventing return to the power supply side, and a trigger is applied to the primary winding of the choke transformer with respect to the polarity of the trigger voltage. A transistor that controls the current flowing through the primary winding so that the transformer is excited within the range that does not cause magnetic saturation of the transformer to the opposite polarity until immediately before the start of discharge, a Zener diode and a resistor to drive the transistor An ion laser device comprising: