JPS63213987A - Detector for output voltage of laser oscillator - Google Patents

Abstract

PURPOSE:To measure output voltage by simple constitution by mounting a current transformer detecting currents on the grounding side of the inductance of a tank circuit between an inverter for a high-frequency power and a laser tube and detecting output voltage from the inverter from the currents of the current transformer. CONSTITUTION:A current transformer 6 is set up on the grounding side of a coil L for a tank circuit 2. Consequently, the voltage of the current transformer 6 is lowered extremely, and low voltage is sufficient as the insulating voltage of the current transformer 6. The ground of the current transformer 6 is separated from a power line for laser discharge, and possibility in which noises, etc., are mixed into the current transformer 6 is also reduced. A controller 7 computes the voltage of a high-frequency power output from a high-frequency power unit 1 from the product of a current signal value from the current transformer 6 and the input impedance of the primary side of a transformer. The current signal value from the current transformer 6 is converted into a digital value by a DA convert er, the L impedance value of the tank circuit 2 is memorized previously as a digital value, and the voltage of the high frequency power can be obtained from the product of both values. An FET, etc., used in the inverter a are protected by the detecting voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an output voltage detection device for a laser oscillator, and particularly to an output voltage detection device for a laser oscillator that can be constructed at low voltage and at low cost.

[Conventional technology]

The electrical impedance of a laser tube changes depending on the state of the internal gas, etc., and therefore the voltage supplied to the laser tube fluctuates. For example, in a laser oscillator having a current feedback loop to the laser tube, if the electrical impedance fluctuates, the supply voltage will naturally fluctuate if the current is controlled to be constant. If this is left as is, it will cause damage to the semiconductors, laser tubes, etc. that make up the inverter in the high frequency power supply. It is also necessary to monitor the output voltage to obtain a stable supply voltage.

Conventionally, this has involved detecting the voltage supplied to the laser tube, raising an alarm when it exceeds a standard voltage, and stopping operation when it exceeds a dangerous voltage. In order to control the output voltage at a constant level, it was necessary to detect and monitor the output voltage. Therefore, in a laser oscillator, monitoring and measuring the supply voltage to the laser tube is one of the important measurement items. Traditionally, these measurements have been made using potential transformers or split capacitors.

[Problem that the invention seeks to solve]

However, when using an instrument transformer, the voltage is quite high, so a transformer with a considerable dielectric strength is required, and since the frequency of the high-frequency power source is high, high-frequency characteristics are also required. This required a very expensive potential transformer.

Additionally, with the method of dividing the voltage using capacitors, it is not possible to separate the power supply line to the laser tube from the ground on the control device side, which poses the problem that there is a high risk of noise entering the control circuit. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an output voltage detection device for a laser oscillator that can be constructed at low voltage and at low cost.

[Failure to solve the problem]

In order to solve the above problems, in the present invention, as shown in FIG. In the output voltage detection device, a current transformer (6) for detecting current is provided on the ground side of the inductance (L) of the tank circuit (2), and the output voltage of the inverter is determined from the current of the current transformer (6). A laser oscillator output voltage detection device is provided, the device being configured to detect the output voltage of a laser oscillator.

[Effect]

Since the current transformer was installed on the ground side of the tank circuit coil,
The voltage of the current transformer is very low.

The output voltage can be calculated from the product of the current value from this current transformer and the inductance impedance of the tank circuit.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention.

In the figure, 1 is an inverter, which rectifies commercial power and converts direct current into high-frequency voltage. 2 is a tank circuit, which is connected in parallel to the output of the inverter 1, and is composed of a coil L and a capacitor C, which are connected in parallel. The tank circuit has a high Q, and C is selected so that the impedance when viewed from the inverter 1 side is substantially pure resistance. 3 is a step-up transformer that steps up the high-frequency power from the high-frequency power supply to a required voltage. A matching circuit 4 performs impedance matching between the transformer 3 and the laser tube 6, and efficiently supplies the power from the inverter 1 to the laser tube. In this embodiment, a π-type matching circuit is used. C1 and C2 are capacitors that constitute a parallel reactance,
Ll is an inductance that constitutes a series reactance.

5 is a laser tube. A tube 51 is made of quartz glass or the like, and a laser medium gas 52 is circulated inside. 53a and 53b are electrodes, and high frequency power is applied to the tube 51 through these electrodes. The laser medium gas 42 in the tube 51 is discharged by a high frequency power source to oscillate and amplify the laser beam. The direction of the laser beam is perpendicular to the plane of the paper.

6 is a current transformer, which is provided on the ground side of the tank circuit coil L. Therefore, the voltage of current transformer 6 is very low;
The insulation voltage of the current transformer 6 is low. Further, the ground of the current transformer 6 is separated from the power line for laser discharge, and there is a low possibility that noise or the like will be mixed into the current transformer 6.

7 is a control device that can calculate the voltage of the high frequency power source output from the high frequency power supply device 1 from the product of the current signal value from the current transformer 6 and the input impedance on the primary side of the transformer. This can be obtained by converting the current signal value from the current transformer 6 into a digital value by a DA converter, storing the impedance value of the tank circuit 2 as a digital value in advance, and then multiplying the two values. This checking voltage determines the F used in the inverter 1.
ET etc. can be protected.

These voltage values are compared with a predetermined reference voltage value, and if the reference voltage value is exceeded by a predetermined value or more, an alarm is displayed. In addition, if this voltage value reaches a dangerous voltage or higher, operation will be stopped. Furthermore, by monitoring this voltage,
It is also possible to control the voltage automatically to keep it constant.

〔Effect of the invention〕

As explained above, in the present invention, the voltage is detected from the current detected from the current transformer provided on the ground side of the coil of the tank circuit, so the insulation voltage of the current transformer is low. An inexpensive current transformer can be used, and the output voltage can be measured with a simple configuration.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] (1) High Q between the high frequency power inverter and the laser tube
In the output voltage detection device for a laser oscillator having a tank circuit, a current transformer for detecting current is provided on the ground side of the inductance of the tank circuit, and the output voltage of the inverter is detected from the current of the current transformer. 1. A laser oscillator output voltage detection device characterized by comprising: