JPS5919388A - Discharge controller for discharge tube - Google Patents

Abstract

PURPOSE:To reduce the size, weight and cost of a discharge controller for a discharge tube by starting the discharge of the tube with low gas pressure, then increasing the gas pressure and increasing the applied DC voltage and current. CONSTITUTION:An AC power from an input unit 1 is raised through the primary voltage converter 11 by a booster circuit 2, converted to a high DC voltage by a rectifier 3, and applied to the anode A of a discharge tube 4. Discharge current is supplied by a constant-current circuit 7 to the cathode C of the tube 4. Carbon dioxide gas is supplied from a carbon dioxide source 5 through a flow controller 51 and a gas supply system L1 to the tube 4. A discharge controller 6 controls the primary voltage variable unit 11, a constant-current circuit 7 and a flow controller 51, a discharge is started with low pressure gas, and then the gas pressure is increased, and the applied DC voltage and current are increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge control device for a gas flow discharge tube that discharges while flowing gas, and in particular to a gas 70-type discharge tube suitable for anode voltage control to obtain high output discharge. The present invention relates to a discharge control device.

The configuration of a conventional discharge tube control device is shown in FIG.

The alternating current voltage from the alternating current input section 1 is converted into an alternating current high voltage by the step-up section 2, and converted into a direct current high voltage by the rectifying section 3,
A voltage is applied to the anode of the discharge tube 4. A current from a constant current circuit 6 is set to a desired value by a discharge current setting section 7 and applied to the cathode C of the discharge tube 4. Gas at a constant pressure is supplied to the discharge tube 4 from the gas supply section 5 through the gas supply system L1 to serve as a discharge source.

The discharge output is obtained by applying a DC high voltage to the anode and flowing a set current to the cathode while flowing gas at a constant gas pressure through the discharge tube.

As shown in Figure 2, due to the negative characteristics of the discharge tube (a phenomenon in which the voltage between the anode and the @ electrode of the discharge tube decreases as the discharge current increases), the discharge starting voltage must be 8. It is necessary to apply a considerably higher anode voltage VA' of the discharge tube than the sustaining voltage V AC after the start of discharge.

As shown in Figure 4, it is necessary to increase the gas pressure P in order to obtain a high-output discharge, but in general, in a discharge tube, when the gas pressure P is increased, the discharge starting voltage 8 increases significantly. do.

Furthermore, as shown in FIG. 3, the difference between the discharge starting voltage V Aa and the sustaining voltage VAC becomes a particularly large p problem when the gas pressure pva<t.

An object of the present invention is to eliminate the above-mentioned drawbacks, and to reduce the maximum anode voltage by starting discharge at a low gas pressure that lowers the discharge starting voltage, and then increasing the gas pressure and setting the anode voltage to an operating value. The goal is to reduce the size, weight, and cost of equipment.

The factors that determine the discharge output W include the anode voltage Vm of the discharge tube, the gas pressure P, and the discharge current iB, and these factors are interrelated. The discharge has a negative characteristic, and as shown in Fig. 2, the discharge starting voltage VAa? :, but once discharged, the anode voltage VA is lowered by the sustaining voltage vAc''! required for discharge.The anode voltage has such a hysteresis characteristic.

The present invention focuses on this point, and at the same time, as shown in FIG. The purpose is to efficiently obtain high output by paying attention to the dependence on the discharge current iB.

Paying attention to the second point, if the gas pressure is set to, for example, Pl as shown in FIG. 3, it is possible to operate at the lowest possible anode discharge starting voltage VACI. but,
As long as the gas pressure remains low at Pl, even if the current i]L is increased as shown in Fig. 4 (IRI<IR*)
High output cannot be obtained. After the start of discharge, the gas pressure P is gradually increased, the anode voltage VA is optimized, and the set discharge current iH is applied to obtain a p1 high output discharge.

The present invention uses the method described above to suppress the voltage applied to the solar pole at a low level and to realize the driving of a high-output discharge tube.

An embodiment of the present invention will be described below with reference to FIG.

The overall configuration consists of input section 1, AC toOV or high frequency (
A negative voltage of several hundred H2 to several tens of KHz is passed through the primary voltage variable section 11, boosted to a high voltage of p6 to 15 KV by the booster circuit 2, and converted to a high voltage of pDC by the rectifier circuit 3. The converted voltage is applied to the anode A of the discharge tube 4. A discharge current that determines the discharge output is supplied to the pole C of the discharge tube from a constant current circuit 7.

On the other hand, carbon dioxide gas is supplied from the carbon dioxide source 5 to the discharge tube 4 through the flow rate controller 51 and the gas supply system LL'. The flow controller used is a combination of an electric circuit and a solenoid valve. The discharge control section 6 controls the anode voltage VA of the discharge tube, the gas pressure P, and the discharge current of 1 m. The discharge control unit 6 controls the discharge procedure based on a signal from the discharge sensor 8 that detects discharge that is input via the discharge detection loop L4, and adjusts the anode voltage of the discharge tube according to the gas pressure situation. is controlled through feedback loop L2.

The discharge sensor 8 converts infrared rays into electrical signals.
For example, a thermomobile type sensor is used.

Note that the start of discharge can also be detected by monitoring the discharge current. In this case, the discharge sensor 8 can be replaced by a current monitor.

The operation of the apparatus of this embodiment will be explained below.

The present invention is characterized in that after starting discharge with a low gas pressure, high output is obtained with a high gas pressure.

The discharge occurs at gas pressure P as shown in FIGS. 3 and 4.

The discharge current in and the anode voltage V are mutually dependent. In order to obtain efficient discharge, the minimum discharge starting voltage Vm shown in FIG. 3 is required.8. Requires. This discharge starting voltage Vmu81
is determined in advance and set in the discharge control section 6.

Further, the discharge sustaining voltage after once discharging is also set in advance to a predetermined value according to the gas pressure in the discharge control unit 6, and after the discharge sensor 8 detects the discharge signal, the discharge sustaining voltage vAc according to the gas pressure is set in advance. lower to

This anode voltage Vm is controlled by the primary voltage variable section 11.

- The primary voltage variable section 11 controls the primary voltage according to the signal from the discharge control section 6.

Specifically, the variable transformer T and electric motor M shown in FIG.
This is possible with a combination of Further, as shown in FIG. 7, rectifier diodes Di, D2 . D3. D4 and transistor T-S
It is also possible to control the amplitude of the 9AC100V voltage by a combination of the following.

Further, control of the high frequency signal can be achieved by controlling the pulse width, controlling the step-up transformer actance, etc.

In either case, the voltage on the negative side is varied to a desired high voltage by the booster circuit 2, and then applied to the anode A of the discharge tube 4.

Next, in order to bring the inside of the discharge tube to the target gas pressure, the discharge control section 6 controls the flow rate controller 51 via the valve control loop L3f to increase the flow rate.

At the same time, the negative voltage variable section 11 controls the anode voltage VA of the discharge tube 4 via the feedback loop L1 to gradually adjust the discharge sustaining voltage to the target gas pressure.

This is because if the gas pressure Pt is suddenly changed, the anode voltage of the discharge tube 4 becomes lower than the discharge sustaining voltage and stops.
This is done to prevent this.

The reason why the gas pressure is set by the flow rate controller 51 is that if the cross section I of the discharge tube is constant, the pressure depends on the flow rate of the gas flowing.

Gas pressure sensor instead of flow controller.

A gas pressure controller consisting of a solenoid valve and a control circuit may be used.

In addition, if necessary, the discharge output monitor 9
It is also possible to input the discharge output value to the discharge control unit 6 through the input terminal 6, and control the gas pressure P, anode voltage VA, and discharge current Imi accordingly, and automatically set the output power to a predetermined value.

When a thermopile is used as a discharge sensor, the discharge sensor 8 and the discharge output monitor 9 can be used in common.

By the above operation, the discharge under the desired high gas pressure can be maintained stably.

Next, a specific example of the discharge control section 6 will be shown.

The discharge control unit 6 performs sequence control such as a series of procedures related to starting and maintaining discharge and reading out stored data. FIG. 8 shows a block diagram of its configuration. An address control section 61 that instructs a series of procedures, a memory section 62 that stores data, a clock 63, and a discharge operation command signal 64 are activated. As shown in FIG. 9, the data structure in the memory section 62 consists of four main parts: first, gas pressure P designation; second, anode voltage Vm designation; third, discharge current i1 designation; Fourth, the next address is specified. When an address is specified by the address control unit 61, the contents of the memory unit 62 corresponding to the address are outputted,
Gas pressure P, anode voltage Vm, and discharge current in are set according to the contents. The next address command is input to the address control section 61. FIG. 10 shows an example of the operation of the discharge control section 6.

The power is turned on at the time of to. Discharge operation command signal 64 is O
During FF', the uoJ'' address is specified. When the discharge operation command signal 64 becomes 0NIC at time t1, the tt 1pp address is specified and the gas pressure Pl+discharge starting voltage V A 111
Set. When the discharge sensor 8 detects discharge at time 12, the clock is counted, and at time t3, '
1'' address and set PI+Vml!+'R12.Then, advance the addresses sequentially and set P u +V to t.
lt l i m tz kFk constant, Pt at time t
2, VAt, in! k, and at time t, Pt, V
Mu! l'Rt t-set and finally set to a high output operating point.

(9) In the examples shown in FIGS. 9 and 1O, in order to avoid dissipating the discharge midway through, an increase in the gas pressure P is specified after specifying an increase in the anode voltage VA and discharge current i1.

Generally, setting gas pressure takes more time than setting voltage or current, so it is possible to specify an increase in gas pressure at the same time as an increase in anode voltage or discharge current. By increasing the number, control becomes easier. Also, even if you change the gas specification, the gas pressure generally changes gradually, so
It is possible to control the number of boosting stages even at the minimum of two stages.

As described above, when the present invention is used, the maximum anode voltage may be about VAaI or VA(!l), which can be significantly lower than VAaB2, which was considered unavoidable in the past.

In an example using a carbon dioxide laser tube, the conventional method requires 15K.
Although a maximum anode voltage of V was required, in the example using the present invention, the voltage could be reduced to 9 KV, and the device (10) could be made smaller and lower in price.

Note that the above is one embodiment for explaining the present invention, and the constant current circuit 7 may be configured by switching one or more resistors, and the polarity of the discharge tube may also be changed in the embodiment. Of course, the directions of the anode A and the cathode C may be alternated.

When configuring a constant current circuit using a resistor, the discharge current specification is replaced by the anode voltage specification.

If the gas flow rate is uniquely determined by the opening/closing degree of the solenoid valve,
The flow controller 51 can be replaced by a solenoid valve.

In addition, if the anode voltage V A s I at which the discharge starts reliably within a predetermined time is known at a low gas pressure P, then v' is substituted for V A 81 in FIGS. 9 and 10. By setting As+(>VAIll)', the discharge sensor 8 shown in FIG. 5 becomes unnecessary.

The present invention adds means for controlling the gas pressure and means for controlling the voltage applied to the anode, and after starting discharge with a low gas, simultaneously increasing the gas pressure and controlling the voltage applied to the anode,
(11) to move it to the final operating point.

According to the present invention, since the anode voltage of the discharge tube can be minimized according to the discharge output, the power supply capacity is reduced. Furthermore, since stable discharge is performed at a low anode voltage, the performance of the device can be improved and the life of the discharge tube can be extended.

Quantitatively, the conventional discharge tube anode voltage required 15 KV, but in the present invention it is 9 KV, which is a p1 reduction of about 40%.

It also reduces power consumption, allowing step-up transformers and rectifier circuits made of high-voltage components to be smaller and lighter.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional discharge tube control device, Figure 2 is a diagram showing discharge principle anode voltage characteristics, Figure 3 is a diagram showing anode voltage vs. gas pressure characteristics, and Figure 4 is discharge output vs. gas. 5 is a block diagram showing an embodiment of the present invention, FIGS. 6 and 7 are circuit diagrams showing an example of a primary voltage variable section, and FIG. 8 is an example of a discharge control section. Configuration diagram, No. 9
The figure shows the contents of the memory in the discharge control section (12), and Figure 1.theta. is a diagram for explaining the present invention in detail. DESCRIPTION OF SYMBOLS 1... Input part, 2... Boost circuit, 3... Rectifier circuit, 4... Discharge tube, 51... Flow rate controller, 5...
... carbon dioxide gas source, 6 ... discharge control unit, 7 ... constant current circuit, 8 ... discharge sensor, 9 ... discharge output monitor,
11...-Next voltage variable section, LL...Gas supply system, L
2... Voltage return loop, L3... Valve control loop, L
4...Discharge detection loop, L5...Discharge flow film constant loop, A...Discharge tube anode, C...Discharge tube cathode, T...
- Variable transformer, M... electric motor, Di, D2. D
3. Di: Rectifier diode, TRf9: Control transistor, 8: Emitter resistor, 61: Address control section, 62: Memory section, 63: Clock, 64: Discharge operation command signal. Agent: Patent attorney Toshiyuki Usuda (13)

Claims (1)

[Claims] In a discharge control device for a discharge tube that applies a DC voltage to the anode while flowing gas and discharges by flowing a discharge current to the cathode, after starting discharge at a low gas pressure, the gas pressure is increased and the DC voltage is applied to the cathode. A discharge control device for a discharge tube, characterized by increasing voltage and discharge current.