JPH01320799A - Lighting of short arc discharge lamp - Google Patents

Abstract

PURPOSE:To reduce light emitting area and improve light collection efficiency by supplying a base current superposed with a specific peak current of a specific frequency to a short arc discharge lamp. CONSTITUTION:A base current supply circuit 12 supplies a base current of a specified value IB to an anode 10a and a cathode 10b of a short arc discharge lamp 10. At the same time, an AC current generating circuit 15 generates an AC pulse current of a specific frequency f and a specific peak current value IP and superposes it on the base current. When the peak current value IP is added to the anode 10a and the cathode 10b, the arc which has been generated increases. When the peak current value passes IP, a large amount of ions generated disappears rapidly. At this time, because the short arc discharge is generated with the peak current value IP of the AC current superposed with the base current IB, the width of an arc discharge passage is narrowed and can be made like a point light source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Field of Application) The present invention relates to a method for lighting a short arc discharge lamp such as an ultra-high pressure mercury lamp that is used as various light sources.

(Prior Art) In an exposure device used for printing patterns on a projector or a printed circuit board, a light source is combined with an optical system such as a reflecting mirror or a lens to collect the light emitted from the light source, and then the light is focused into a predetermined area. The device is configured to obtain illumination light. Therefore, the light source used in these devices preferably acts as a point light source, and short arc discharge lamps such as ultra-high pressure mercury lamps and xenon lamps are often used. As specific examples of short arc discharge lamps, for example, xenon lamps are used in movie projectors, and ultra-high pressure mercury lamps are used in semiconductor wafer exposure equipment. By the way, in order to improve the efficiency when such a short arc discharge lamp is used, the following method has been carried out. That is, when a projector 5 xenon lamp is used, for example, as shown in Japanese Patent Laid-Open No. 63-34897, a large direct current is supplied to the xenon lamp in conjunction with the shutter of the projector only when the shutter is opened. That's what I do. In addition, when an ultra-high pressure mercury lamp is used in a semiconductor wafer exposure apparatus, for example, as shown in Japanese Unexamined Patent Publication No. 60-57930, it is necessary to use a large DC current only during exposure when repeatedly performing multiple exposures. It is designed to supply high pressure mercury lamps.

In other words, in any of these methods, a large amount of light is obtained by supplying a large current to the short arc discharge lamp only when light is required.

However, the above methods have a problem in that the light generated during arc discharge cannot be used efficiently.

That is, to explain the anode 2 and cathode 3 disposed inside the arc discharge tube 1 shown in FIG. 6, when a large current is instantaneously supplied between the anode 2 and the cathode 3, the arc is generated as shown in 4a. In this case, the width of the arc discharge path becomes wider and the light emitting area becomes larger. This is due to the diffusion of mercury ions and electrons near the picture electrodes 2 and 3 due to the large current. However, it no longer acts as a point light source, and therefore the light emitted from the light source cannot be used effectively.

(Problems to be Solved by the Invention) As described above, the light emitting area due to arc discharge becomes large, and there is a problem in that the synchrotron radiation cannot be used effectively.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for lighting a short arc discharge lamp that can prevent arc spread even when a large current is supplied.

[Structure of the invention] (Means and effects for solving the problems) - The present invention provides base current 1. In addition to supplying this base current, when the frequency is f and the peak current value is IP, an alternating current that satisfies the following relationships: 3≦f≦1.0 (kHz) 0.4≦I p / I s≦1 This is a method for lighting a short arc discharge lamp, which is characterized by overlapping.

Further, the present invention supplies the base current IB, and the frequency of the base current IB is f1, where IP is the peak current value, 0.3≦f≦10 (kHz), 0.4≦IP/1. A lighting current obtained by superimposing an alternating current that satisfies the relationship of ≦1 and a base current value of 1. This is a lighting method for a short arc discharge lamp in which a low lighting current having a current value of 10 to 70% of the current value is repeatedly supplied.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a lighting circuit for a short arc discharge lamp to which the first method of the present invention is applied. In the figure, 10 is a short arc discharge lamp such as an ultra-high pressure mercury lamp or a xenon lamp, and current is supplied to this short arc discharge lamp 10 from two systems. That is,
One of the systems is equipped with a DC power supply 11 , and the DC output of this DC power supply 11 is applied to a base current supply circuit 12 . This base current supply circuit 12 supplies a predetermined base current between the anode 10a and the cathode 10b of the short arc discharge lamp 10.

Further, the other system is provided with a DC power supply 14 , and the DC output of this DC power supply 14 is applied to an AC generator circuit 15 . This alternating current generating circuit 15 superimposes an alternating current having a frequency f and a peak current value IB on the base current. Here, this alternating current is set so that the following relationships are satisfied: 0.3≦f≦10 (kHz) 0.4≦IP/■B≦1. Further, a timer 16 is connected to the AC generating circuit 15, and the timing of generation of the AC current is determined by the timer 16.

Next, each lighting operation in the circuit configured as described above will be explained.

The base current supply circuit 12 supplies a base current of a predetermined value IB between the anode 10a and the cathode 10b of the short arc discharge lamp 10. At the same time, the AC generating circuit 15 generates an AC pulse current having a frequency f and a peak current value I. As a result, an alternating current is superimposed on the base current, and a current as shown in FIG. 2 is supplied between the anode 10a and the cathode Ob of the short arc discharge lamp 1o. However, when the peak current value IP is supplied between the anode 10a and the cathode 10b, these two electrodes 10a.

10b increases.

Then, when the peak current value IP passes, the base current becomes I,
As a result, residual ions generated in large quantities when the peak current is supplied quickly disappear. Moreover, the short arc discharge at this time is caused by the base current I
Since this occurs due to the peak current value IP of the alternating current superimposed on B, the width of the arc discharge path 4b becomes narrower as shown in FIG.

In other words, it becomes close to a point light source. In other words, residual ions generated in large quantities when a peak current is supplied are quickly annihilated by a current in the negative direction with respect to the base current, and then the next peak current is supplied, so that Since no discharge path is generated in the direction perpendicular to the arc, the spread of the arc can be prevented.

As described above, an alternating current with a peak current value ■ρ at a frequency f is superimposed on the base current 1B to generate a short arc discharge lamp 10.
Since the light is supplied to the light source, the width of the arc can be narrowed and its light emitting area can be reduced, thereby making it possible to closely approximate a point light source.

Therefore, when condensing light using an optical system or the like, the condensing efficiency can be increased. Further, since the current value is lower than the base current IB due to the alternating current, residual ions caused by the arc current can be quickly eliminated.

Next, when applied to an actual ultraviolet dryer or the like, as shown in FIG. 3, the generation of alternating current is stopped during period F of period S when no drying operation is performed. Note that this operation is performed by timer 16.
This specifies the period in which alternating current is generated and the period in which it is not generated.

By creating a period in which no alternating current is generated in this way, alternating current can be superimposed in accordance with the operating state of target equipment such as an ultraviolet dryer, and in this case, power can be reduced.

Next, an embodiment of the second invention will be described with reference to the drawings.

In FIG. 1, as mentioned above, 10 is a short arc discharge lamp such as an ultra-high pressure mercury lamp or a xenon lamp, and current is supplied to this short arc discharge lamp 10 from two systems. That is, one of the systems is equipped with a DC power supply 11 , and the DC output of this DC power supply 11 is applied to a base current supply circuit 12 . This base current supply circuit 12 supplies a predetermined base current and a low lighting current between the anode 0'a and the cathode 10b of the short arc discharge lamp 10. Specifically, the circuit 12 supplies a predetermined base current and a low lighting current between the anode 0'a and the cathode 10b of the short arc discharge lamp 10. It has a function of lowering the lighting current to a low level that maintains the discharge to a minimum level and alternately outputting current levels (1)8 and (2)8'.

In addition, the relationship between current level E8 and ■B- is 0.1≦IH
-/IB≦0.7 is set. Further, a timer 13 is connected to this base current supply circuit 12, and this timer 1
3, the period between current levels IB and ■B- is set.

The other system is equipped with a DC power supply 14, and the DC output of this DC power supply 4 is applied to an AC generation circuit 15. This alternating current generating circuit 15 superimposes an alternating current having a frequency f and a peak current value IB on the base current. Here, this alternating current is set so that the following relationship holds true: 3≦f≦10 (kHz) 4≦p/IB≦1. Further, a timer 16 is connected to the AC generating circuit 15, and the timing of generation of the AC current is determined by the timer 16.

Next, each lighting operation in the circuit configured as described in section 2 will be explained.

The base current supply circuit 12 has a predetermined value of 1. A base current of 1 is supplied between the anode 10a and the cathode 10b of the arc discharge lamp. At the same time, the AC generating circuit 5 generates an AC pulse current having a frequency f and a peak current value IP.

As a result, an alternating current is superimposed on the Haas current, and a current as shown in FIG.
b. However, when the peak current value IP is supplied between the anode 10a and the cathode 10b, these two electrodes 10a.

10b increases.

Then, when the peak current value IP passes, the base current increases to 1.
As a result, residual ions generated in large quantities when the peak current is supplied quickly disappear. Moreover, the short arc discharge at this time is caused by the base current I
Since this occurs due to the peak current value IP of the alternating current superimposed on D, the width of the arc discharge path 4b becomes narrower as shown in FIG.

In other words, it becomes close to a point light source.

Here, as shown in FIG. 4, the base current supply circuit 12 supplies the lighting current IB- to the base current from 10 to 10 of IB during the period F in which no alternating current is generated according to the operating state of the target device.
Reduce to 70% value.

This low lighting current IB' is the minimum value that can maintain arc discharge, and the ratio of the alternating current IB and 18- is as described above.

By lowering the base current in this way, it is possible not only to achieve the same effect as in the case of the first invention described above, but also to be suitable for application to exposure of semiconductor wafers, for example, and to save power and short arc. The lifespan of discharge lamps can be extended.

Next, a modification will be explained using FIG. 5. The difference from the above embodiment is that the low lighting current is a direct current having an amplitude. That is, in this case, the base current supply circuit 12 reduces the base current from IB to IB- during the period F in which no alternating current is superimposed, depending on the operating state of the target device, as in the embodiment. ``At the same time, the AC generating circuit 15 lowers the peak current value IP to IP- without changing the frequency f.

The peak current value decreased at this time 1. - and base current value 1. - It is preferable to set the ratio to ■p/I B -≦1. In this way, the peak current value of alternating current 1. - can be lowered and superimposed to provide a low lighting current, thereby saving power.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a lighting method for a short arc discharge lamp that can increase the light collection efficiency even when light is collected by reducing the light emitting area.

[Brief explanation of the drawing]

, 8. Figs. 1 to 5 are diagrams for explaining a lighting circuit to which the short arc discharge lamp lighting method according to the present invention is applied, in which Fig. 1 is a block diagram and Figs. 2 to 5 are diagrams. 6 is an operation timing diagram showing each lighting method, and FIG. 6 is a diagram showing an arc generation state. 10...Short discharge lamp, 11.14...DC power supply, 12...Base current supply circuit, 13.16.
...Timer, 15...AC generating circuit. Applicant's agent Patent attorney Takehiko Suzue = 13 - Figure 4 □ I I I! Whistle At121', J-1 Fig. 5

Claims (1)

[Claims] (1) When a base current I_B is supplied and the frequency of this base current is f and the peak current value is I_P, 0.3≦f≦10 (kHz) 0.4≦I_P/I_B≦ 1. A method for lighting a short arc discharge lamp, characterized by superimposing alternating current that satisfies the following relationship. (2) Supplying base current I_B and satisfying the following relationships: 0.3≦f≦10 (kHz) 0.4≦I_P/I_B≦1, where the frequency of base current I_B is f and the peak current value is I_P. A method for lighting a short arc discharge lamp, characterized in that a lighting current in which an alternating current is superimposed and a low lighting current having a current value of 10 to 70% of the base current value I_B are repeatedly supplied.