JPS58218184A - Laser lighting circuit - Google Patents

Abstract

PURPOSE:To prevent the discharge between cathode and gas pressure detecting element from happening simplifying the circuit and improving mounting density of the overall circuit by a method wherein a laser lighting circuit is excited by 2 power supplies +VDC and -VDC while a cathode potential is set up nearly as the potential of ground line G. CONSTITUTION:When an anode 4 is supplied with high voltage +VDC and a heater 10 is supplied with heater current from a metallic vapor control circuit 6, a laser lighting circuit is subject to mixed discharge of gas and metallic vapor between the anode 4 and a cathode 22 oscillating laser. During the laser oscillation, the discharge current is kept constant by means of a constant current circuit 24 while the voltage between anode 4 and the cathode 22 is also kept constant due to the metallic vapor pressure controlled by the metallic vapor pressure control circuit 6 based on the cathode potential detected. Furthermore, the gas pressure in a discharge tube 2 is always kept constant for a long time due to a buffer, gas pressure control circuit 20.

Description

[Detailed description of the invention] The present invention relates to a lighting circuit for a gas laser.

In general, for gas laser tubes, in order to obtain stable light output over a long period of time, it is necessary not only to simply discharge direct current from the gas laser tube, but also to provide the following control circuits. .

(1) Constant current circuit to always flow a constant current to the laser tube.

(2) A metal vapor pressure control circuit that controls the vapor pressure inside the laser tube in response to the tube voltage so that the tube voltage of the laser tube is always maintained at an optimal value.

(3) A gas pressure control circuit that detects a drop in gas pressure inside the tube when the laser tube is turned on for a long period of time and replenishes gas inside the tube.゛In the conventional gas laser lighting circuit, a constant current circuit is connected to the cathode, a metal vapor pressure control circuit is connected to the anode, and a gas pressure control circuit is connected to the gas pressure detection element, and these circuits are connected to each other independently. and is connected to a ground line G*G1 eG2 having an independent ground potential for the following reasons.

The metal vapor pressure control circuit is connected to the anode to detect the voltage of the laser tube, but the common potential of the control system, ie O
When connected to the ground line G having a V level, when the voltage of the laser tube changes, the impedance change is compensated for by the impedance of the constant current circuit.
The overall level does not change, and the voltage of the radar tube cannot be accurately detected. Therefore, the metal vapor control circuit has a ground line G with a common potential of approximately 600
It must be connected to a ground line G, which has a high potential of ~800v. In addition, the gas pressure control circuit is
It is connected to the ground line G2 which is insulated from the common potential through the gas pressure sensing element, but if it is connected to the ground line G having a common potential, there will be a gap between the cathode and the gas pressure sensing element. There is a risk that a potential difference will occur and a discharge will occur between the cathode and the gas pressure sensing element. Therefore, the gas pressure sensing element is connected to the ground line G2 having a potential that is approximately insulated from the cand potential.

However, the number of times the laser was lit by the employee mentioned above...□.

It has been pointed out that there are more problems with roads. First, since each circuit has a potential difference of 1, it is necessary to use fixed components for safety reasons, and the cost of the entire circuit cannot be reduced. Secondly, since each circuit has a potential difference, the packaging density of the entire circuit cannot be improved, and the entire device becomes larger.

Thirdly, because the voltage that can be applied to the anode is extremely high compared to the ground line G having a common potential, G1, especially the components constituting the metal vapor control circuit, are subject to limitations and have extremely narrow selectivity.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a lighting circuit for a gas laser that has a simplified circuit configuration and is operated reliably.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas laser lighting circuit according to an embodiment of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, the anode 4 of the laser discharge tube 2 is connected to a high voltage power supply +vDo, for example 1, @-1-2
00"'.7°1it(ffK#[l"; IIc,.

The heater ``W'' current is controlled according to the fluctuation of this anode potential, and the
A metal vapor pressure control circuit 6 is connected to adjust the vapor pressure. The metal vapor pressure control circuit 6 is provided in the metal reservoir 8 of the laser discharge tube 2, and controls the Ov potential by heating the gold ingot JO, for example, Cd, in the metal reservoir 8, and generates Cd vapor. Connected to ground line GK.

A gas replenishment container 14 provided in the discharge tube 2 For example, in a He gas replenishment container, when the gas pressure in the discharge tube 2 decreases, the gas replenishment container 14 is heated and gas is replenished from this container 14 into the tube. A heater J6 is provided for this purpose. This heater 16 includes a buffer gas pressure control circuit 20 for controlling the current supplied to the power supply vDD and the heater 16 according to the gas pressure in the pipe detected by a gas pressure detection element 18, for example, a resistor.
The buffer gas pressure control circuit 20 is connected to the ground line GK via the gas pressure detection element 18. The cathode 22 is set to approximately the potential of the ground line G, that is, approximately Ov potential, and this cathode 22 is connected to a constant current circuit 24 for maintaining the tube current flowing between the anode and the cathode approximately constant. The current circuit 24 is connected to a negative power supply -vDC, for example, a voltage source of -2000V. The constant current circuit 24 is also connected to a discharge start signal generation circuit 26 which detects the tube current and generates a discharge start signal to notify that discharge has started. It is connected to a defect 1/notification circuit 28 which notifies that a defective condition has occurred. The discharge start signal generation circuit 26 and non-lighting warning circuit 28 are similarly connected to the ground line G.

According to the laser lighting circuit as described above, when a high voltage +vDc is applied to the anode 4 and a heater current is supplied to the heater 10 from the metal vapor pressure control circuit 6, gas and metal are generated between the anode 4 and the cathode 22. A mixed discharge of vapor occurs and a laser is generated. During laser oscillation, the discharge current is kept constant by the constant current circuit 24, and
The voltage between the anode 4 and the cathode 22 is maintained constant because the metal vapor pressure is adjusted by the metal vapor pressure control circuit 6 based on the detected cathode potential. Moreover, it is constant for a long time.

The gas pressure within the discharge tube 2 is maintained constant by the buffer gas pressure control circuit 20. Therefore, stable discharge occurs in the laser emitting tube, and the life of the laser emitting tube is extended.

In this single laser lighting circuit, whereas the conventional circuit used a single power supply, the circuit was damaged by two power supplies of 10vDC and 'DC, and moreover, the cando potential was approximately the potential of the ground line G, that is, 0. It is set to V. Therefore, discharge at the cathode 22 and the gas pressure sensing element J811J) can be prevented. Moreover, since each circuit is connected to the common ground line G, the circuit can be simplified, and the packaging density of the entire circuit can be improved. As a result, the device can be made smaller and lower in price.

[Brief explanation of drawings]

The figure is a circuit diagram showing an embodiment of the laser lighting circuit of the present invention. □ 2... Laser - discharge tube, 4◆... Anode, 8...
・Kin Udam, xo, 1e...Heater, 18...Gas pressure sensing element, 22...Cathode.

Claims (1)

[Claims] a high-voltage positive power supply connected to the anode of the Rede discharge tube; a constant current circuit that sets the cathode potential to earth potential, is connected to the cathode, and maintains the discharge current substantially constant;
and a negative power supply connected to the constant tit circuit.