JPH0433151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application This invention relates to a detection device for arc discharge (abnormal discharge) in a gas laser oscillator.

b. Prior Art The discharge of gas laser oscillators is often caused by glow discharge, and when arc discharge occurs in such an oscillator, a large current flows and is dangerous. Therefore, if arc discharge occurs, it must be detected immediately. and needs to be removed. Since arc discharge generally generates strong light, this detection device uses a light method that uses a photodetector to detect arc light, as well as a current sensor installed in the discharge circuit to detect arc discharge using changes in current. There are also electrical detection methods.

C. Problems to be Solved by the Invention As mentioned above, there are two types of arc discharge detection devices: optical type and electric type. In the case of optical type, it is necessary to provide a window in the discharge vessel to allow light to pass through. When the photodetection element is provided in the discharge vessel without providing a window, it is necessary to take measures so that the high voltage of the discharge section does not affect the photodetection element. Furthermore, arc discharge may not be accompanied by strong light, and in such cases it cannot be detected by this device. In the electric method, the total current of the discharge circuit is generally detected, so even if only one of the plurality of cathodes generates arc discharge, the increase in current relative to the total current is small, and the detection accuracy of arc discharge is low. It is also possible to provide a current sensor for each cathode, but this increases the complexity of the device.

The present invention improves the above-mentioned problems and provides a device that can stably detect arc discharge of a glow discharge electric body laser oscillator equipped with a plurality of cathodes using a simple circuit configuration. The purpose is to

d Means for Solving the Problem In order to achieve the above object, the present invention connects a plurality of cathodes of a glow discharge electric body laser oscillator in parallel via diodes, and the voltage at the connection point is The gist of the configuration is that a comparator is provided that outputs a signal when the voltage is higher than a set reference voltage.

e Effect Since the structure is as described above, the voltage at the connection point of multiple cathodes connected via diodes is
It is always equal to the highest voltage among the individual cathode voltages of the plurality of cathodes. Since a cathode with a high voltage has a high probability of generating an arc, the voltage at the connection point is compared with an appropriately set reference voltage using a comparator, and if the voltage at the connection point is higher than the reference voltage,
It can be determined that an arc is occurring based on the output signal of the comparator. The accuracy of this device depends on the setting value of the reference voltage, and the embodiment section shows an example of the device for setting the reference voltage.

f Example Next, an example of the present invention will be described based on the drawings. FIG. 1 is an explanatory diagram of the apparatus of the present invention.
Inside the discharge vessel 3 of the glow discharge electric body laser oscillator 1, one anode A and a plurality of cathodes K ₁ to K ₄ face each other, and each cathode is connected to a stabilizing resistor R ₁ to R ₄ . At the other ends of the anode A and the stabilizing resistors _R1 to _R4 ,
The positive and negative electrodes of the power source 5 are connected to each other. Each cathode K ₁ ~ _{K 4} is connected to a diode D ₁ ~
_D4 , and the connection point P is connected to one input signal terminal of the comparator 7, and an appropriately set reference voltage is applied to the other input signal terminal of the comparator 7. has been done. The output signal terminal of the comparator 7 is connected to an alarm device or the like (not shown).

In such a configuration, when a discharge occurs between the anode and multiple cathodes, the current of each cathode K ₁ to _{K 2} is
In the case of glow discharge, the voltages are approximately equal, and the voltages of each cathode are also approximately equal. However, if arcing occurs in even one of the cathodes, the cathode current that caused the arcing increases rapidly, and the voltage at that cathode rises rapidly. Since the plurality of cathodes are connected in parallel through the diodes at point P, the voltage at point P is the highest voltage of each cathode voltage. This voltage is compared with an appropriately set reference voltage in a comparator, and if arc discharge occurs and the cathode voltage is higher than the reference voltage, the comparator outputs a signal.
It can activate alarms, etc.

As the reference voltage, the cathode voltage during glow discharge can be used and is shown in FIG. Even during glow discharge, the current fluctuates depending on the setting of the discharge current, but these fluctuations are generally small, and the reference voltage is smoothed through an integrating circuit (smoothing circuit) 9 as shown in the figure. In this circuit, by appropriately selecting the values of capacitor C and resistor _R5 , comparator 7 will not detect slow fluctuations in discharge current such as glow discharge, since both input voltages are equal. However, if there is a sudden change in the discharge current, such as a transition from glow discharge to arc discharge, this can be detected immediately. The reason for this is that the voltage of the capacitor provided in the integrating circuit, that is, the reference voltage, does not rise suddenly even if arc discharge occurs, which causes a difference between the two input voltages of the comparator 7.

If the withstand voltage of diodes connected to multiple cathodes is low, in order to reduce the voltage applied to the diodes, connect another resistor in parallel to the stabilizing resistors _R1 to _R4 , and divide the voltage from the middle of this resistor. The voltage may be taken out, or a divided voltage may be taken out directly from the middle of the stabilizing resistor.

g. Effects of the Invention As understood from the above description, the present invention has the structure set forth in the claims, and thus provides an arc discharge detection device for a gas laser oscillator with a simple structure and high stability. can do.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the device of the present invention, and FIG. 2 is a reference voltage setting circuit diagram. Explanation of symbols representing main parts in the drawings, 1...
...Gas laser oscillator, 3...Discharge vessel, 5...Power source, 7...Comparator, 9...Integrator circuit, A...Anode, _K1 to _K4 ...Cathode, _D1 to _D4 ...Diode ,
R ₁ ~ R ₄ ... Stabilizing resistance.

Claims (1)

[Claims] 1 A plurality of cathodes are connected in parallel via diodes, and a comparator is provided that outputs a signal when the voltage at the connection point is higher than a separately set reference voltage. An arc discharge detection device for a gas laser oscillator, characterized in that: 2. The arc discharge detection device for a gas laser oscillator according to claim 1, wherein the voltage at the connection point of the plurality of cathodes is input to an integrating circuit, and the output voltage thereof is used as a reference voltage of the comparator.