Coherent light generators – Particular component circuitry – Optical pumping
Patent
1988-10-27
1989-10-24
Scott, Jr., Leon
Coherent light generators
Particular component circuitry
Optical pumping
372 21, H01S 300
Patent
active
048766895
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an output voltage detecting device in a laser oscillator, and more particularly to an output voltage detecting device in a laser oscillator, in which an output voltage can be detected with a circuit having a simple configuration.
A laser tube for use in a gas laser device has an electrical impedance which varies depending upon an interiorly confined gas status. As a consequence, a voltage supplied to the laser tube varies. For example, in a laser oscillator having a current feedback loop with which a current is fedback to the laser tube, the variation in the electrical impedance of the laser tube causes the supply voltage to vary since the current is being controlled to be constant. If this condition remains semiconductor elements, the laser tube or other elements forming an inverter are damaged.
In view of the foregoing, it is a conventional practice to detect the voltage supplied to the laser tube. When the resultant voltage is above a reference voltage, an alarm is generated. When the detected voltage is above a danger-level voltage, the driving is stopped. In addition, it has been necessary to detect and monitor the output voltage in order to control the output voltage to be constant.
However, when a transformer is used, it is required to have a considerably high voltage insulation resistivity. The transformer is further required to have a high frequency characteristic attendant to the high frequency power supply unit. For such reasons, the transformers which are extremely expensive have to be employed.
A method in which the voltage is divided by capacitors has a problem in that a power supply line led to the laser tube cannot be isolated from a ground connection of a control apparatus, so that noise is liable to be introduced into a control circuit.
SUMMARY OF THE INVENTION
An object of the present invention is to resolve the foregoing problems and to provide an output voltage detecting device in a laser oscillator, in which an output voltage is detected with a circuit having a simple configuration, and an abnormal voltage can be monitored.
Another object of the present invention is to provide an output voltage detecting device in a laser oscillator, which is operable at a low voltage and producible at a low cost.
In order to resolve the foregoing problems, the present invention provides an output voltage detecting device in a laser oscillator in which laser oscillation occurs upon application of a high frequency voltage to a laser tube. The device comprises a voltage detection circuit connected to an input of an inverter for applying the high frequency voltage. The voltage detecting circuit includes a nonlinear element and a reference voltage, and a current transformer for detecting a current flowing in the nonlinear element. An abnormality of the output voltage is detected in accordance with the current flowing in a nonlinear element.
The nonlinear element has a nonlinear point at a voltage slightly higher than a regular voltage of a converter, and a current vs. resistance characteristic is abruptly changed when the voltage applied thereto exceeds the nonlinear voltage point. Accordingly, when the output voltage of the converter exceeds the reference voltage, a current flows abruptly in the nonlinear element. Thus, upon detection of the current by means of the current transformer, an abnormal voltage is detected.
Details of other aspects of the invention will become apparent when read in conjunction with the later described embodiments and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a first embodiment according to the present invention;
FIG. 2 is a graph of the relationship between a voltage and a current of a varistor B;
FIG. 3 is a block diagram of a second embodiment according to the present invention; and
FIG. 4 is a block diagram of a third embodiment according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first embodiment of the present invention will now
REFERENCES:
patent: 4823350 (1989-04-01), Tamazaki
Fanuc Ltd.
Jr. Leon Scott
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