JPH025395A - Lighting of short-arc discharge lamp - Google Patents

Abstract

PURPOSE:To reduce a luminous face and increase the light collecting efficiency by repeatedly superimposing the pulse current with a specific value on the base current after the specific rest period for lighting. CONSTITUTION:The DC output of a DC power source 11 invariably feeds the base current IB with the same level to the anode 10a and the cathode 10b of a short-arc discharge lamp 10 via a base current feeding circuit 12. The output of a DC power source 14 is applied to a pulse generating circuit 15. The circuit 15 repeatedly superimposes the pulse current shown by the equation 1 to the base current IB after the pulse rest period when no arc discharge is performed. In the equation, T is the reset period, Ip is the peak current value, tP is the pulse width. The potential difference between the anode 10a and the cathode 10b of the discharge lamp 10 becomes larger than when only the base current is fed, the discharge lamp 10 is discharged. When the pulse rest period T is provided, the width of the arc can be narrowed, the discharge lamp approximates a point light source, thus the luminous area can be reduced, the light collecting efficiency can be increased.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to xenon lamps that are applied as various light sources;
This invention relates to a method of lighting a short arc discharge lamp such as an ultra-high pressure mercury lamp.

(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. For this reason, the light source used in these devices is preferably one that acts as a point light source, and for example, 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.

In other words, if a xenon lamp is used in the projector,
For example, as shown in Japanese Patent Application Laid-Open No. 63-34897, a large direct current is supplied to a xenon lamp only when the shutter is opened in conjunction with the shutter of the projector. 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 method has a problem in that the light generated during arc discharge cannot be used efficiently.

That is, to explain the anode 2 and cathode 3 arranged inside the arc discharge tube 1 shown in FIG. 5, when a large current is instantaneously supplied between the anode 2 and the cathode 3, the arc will be 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 electrode 2.3 due to the large current. Therefore, it no longer acts as a point light source, and therefore the light emitted from the light source cannot be used effectively.

(Problem to be solved by the invention) As described above, the light emitting area due to arc discharge increases,
There was a problem in that synchrotron radiation could not 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 supplies a base current, and applies a pulse current having a pulse width tP and a peak current value IP to the base current after a pulse rest period T. Repeatedly superimpose base current 1[1+ pulse width tP, peak current value I
Lighting of the short arc discharge lamp by setting P and pulse pause period T to the following relationships: 0.03≦tP≦3 (+n5) 0.1≦T≦10 (ms) 1.4≦I p / I n≦6 It's a method.

Further, the present invention is a lighting method in which a period of applying a high lighting current and a low lighting current is repeated, and the high lighting current supplies a base current IB and a peak current value IP of the base current Ia with a pulse width tP. A pulse current is repeatedly superimposed after a pulse rest period T, and a base current IB and a pulse width tP.

The relationship between peak current value IB and pulse pause period T is 0, 03 ≦ 1 2 ≦ 3 (ms) 0, 1
≦T≦ 10 C++++s) 1, 4≦ ■ P
/IB≦6, and the low lighting current value 18゛ is a lighting method for short arc discharge lamps that satisfies the relationship 1B-/IB≧0.2 compared to the base current value IB of high lighting current. .

(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 always supplies a base current IB of the same level between the anode Oa 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 a pulse generation circuit 15 . This pulse generating circuit 15 repeatedly superimposes a pulse current having a peak current value IP with a pulse width tP on the base current after a pulse rest period T during which no arc discharge is performed.

Here, this pulse current has the following relationship, that is, 0.03≦
The settings are such that tP≦3 (ms) 0.1≦T≦10 (ms) 1.4≦IP/IB≦6. Further, a timer 16 is connected to the pulse generation circuit 15, and the timing of generation of the pulse 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 pulse generating circuit 15 generates a pulse current after the pulse rest period T has elapsed. As a result, the pulse current is superimposed on the base current and the second
A current as shown in the figure is supplied between the anode 10a and the cathode 10b of the short arc discharge lamp 10. However, when only the base current of the predetermined value IB is supplied, arc generation can be maintained at a minimum between the anode 10a and the cathode 10b of the short arc discharge lamp 10, and the enclosed metal such as mercury is condensed. It is in a state where it does not. Further, when a pulse current having a pulse width tP and a peak current value IP is supplied, discharge is promoted and radiation increases.

Here, Tables 1 and 2 show the pulse width tp, the time difference between the pulse pause period T and the pulse width tP, and the base current I.
The relationship between efficiency and the like when changing the ratio between B and the peak current value IP is shown. Note that Table 1 shows the results for a xenon lamp, Table 2 shows the results for an ultra-high pressure mercury lamp, and for comparison, the results for a lamp in which direct current was continuously supplied are also shown.

Table 1 Table 2 Specifically, Table 1 shows the results of efficiency and relative illuminance tests performed using a 1 kW xenon lamp, and the xenon lamp was adjusted to about 1 kW. In addition, the efficiency is the illumination intensity per unit electric power, and is rlooJ in the case of DC lighting.
Relative illuminance is the illuminance on the screen under certain conditions, and in the case of DC lighting, it is expressed as rl.
It is shown as a relative value expressed as oOJ. As can be seen from the table, high efficiency is achieved when the pulse width tP is in the range of 0.03 to 3 (ms).

Furthermore, if T-tP is too short, it becomes close to continuous arc discharge, and on the other hand, if it is too long, the pulse current ratio decreases, and in either case, efficiency deteriorates. However,
From the test results, the optimal T-tP is in the range of 0.1 to 10 IIs. This is because the residual ions generated when the peak current is supplied disappear during the period when only the base current is applied, that is, during the pulse pause period, and then the next peak occurs. [Since iA is supplied, a discharge path greater than the base current is not generated in the width direction of the arc (direction perpendicular to the direction between the electrodes), preventing the arc from spreading, and as a result, the synchrotron radiation can be used effectively.] Become. Furthermore, if the ratio of I p / I B is set to 6 or more,
Due to large fluctuations in the current flowing through the xenon lamp, the anode 10a and cathode 10b are likely to be thermally damaged, and the life of the xenon lamp is extremely shortened.

Furthermore, if the IP/IB ratio is 1.4 or less, it becomes impossible to increase the efficiency. Therefore, the ratio of Ip/IB is 1,
A range of 4 to 6 is optimal. Note that each range of xenon lamps shown in Table 1 falls within each range of ultra-high pressure mercury lamps.

Table 2 shows the results of testing the time required for curing photoresist using an ultra-high pressure mercury lamp.The time required for curing, that is, the exposure time, is 13% compared to the case of direct current lighting.
It turns out that it is short and hardens. Note that each range of ultra-high pressure mercury lamps shown in Table 2 falls within each range of xenon lamps.

As described above, since a pulse current is superimposed on the base current every pulse pause period T and is supplied to the short arc discharge lamp 10, the width of the arc can be narrowed and its light emitting area can be reduced, thereby making it possible to become a point light source. can be very approximated. Therefore, when condensing light, the condensing efficiency can be increased.

Next, as shown in FIG. 3, the generation of the pulse current is stopped during an arbitrary period F of the period S in which no drying operation is performed. Note that this operation may be configured such that a period in which a pulse current is generated and a period in which a pulse current is not generated can be specified by a timer 16 added to the pulse generation circuit.

By creating a period in which no pulse current is generated in this manner, arc discharge can be performed in accordance with the operating state of target equipment such as an ultraviolet dryer.

Next, an embodiment of the second invention will be described with reference to FIGS. 1 and 4.

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, the negative system is equipped with a DC power supply 11, and the DC output of this DC power supply 11 is applied to the base current supply circuit 12. This base current supply circuit 12 is connected to an anode 10a and a cathode 1 of a short arc discharge lamp 10.
A base current IB at high lighting current is supplied between 1.0b and low lighting current 1.0b. -, specifically, the function of constantly supplying a base current at the same level IB, and the current value 1.0 that can maintain arc discharge at a minimum for a predetermined period R of period S. - and alternately outputs current levels IB and IB'.

The relationship between current level ■B and IB- is IB'/IB
It is set so that ≧0.2 holds true. Also, a timer 3 is connected to this base current supply circuit 12, and this timer]
3, the period between current levels 1B and ■B' is set.

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 a pulse generation circuit 15 . This pulse generation circuit 15 has a pulse rest period T during which arc discharge is not performed with respect to the base current at the time of high lighting current.
After that, a pulse current having a peak current value IP with a pulse width tP is repeatedly superimposed. Here, this pulse current has the following relationship: 0, 03 ≦ tP ≦ 3 (ms) 0, 1 ≦
T≦10 (ms)1, 4≦I p /
It is set so that I B ≦6. or,
A timer 16 is connected to the pulse generation circuit 15, and the timer 16 determines the timing at which the pulse current is generated.

If an example of such a lighting device is used, a period in which the peak current is superimposed and a period in which the current value is reduced compared to the base current value are repeated, so the conveyance state and operation of the irradiated object such as dried material can be changed. By synchronizing the state and the low current supply section, in addition to the effect of the second invention, there is also the advantage of saving power.

In other words, by lowering the base current, not only can the same effects as in the first invention be achieved, but also
For example, it is most suitable for application to exposure of semiconductor wafers, and furthermore, it can save power and extend the life of short arc discharge lamps.

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 described in detail 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 DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 4 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 configuration diagram, and FIG. 4 to 4 are operation timing diagrams showing each lighting method, and FIG. 5 is a diagram showing an arc generation state. 10...Short arc discharge lamp, 11.14...DC power supply, ]2...Base current supply circuit, 13°16.
...Timer, 15...Pulse generation circuit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] (1) A base current I_B is supplied, and a pulse current of a peak current value I_P with a pulse width t_P is repeatedly superimposed on this base current after a pulse rest period T, and at this time, the base current I_B, The pulse width t_P, the peak current value I_P, and the pulse pause period T are set to the following relationships: 0.03≦t_P≦3 (ms) 0.1≦T≦10 (ms) 1.4≦I_P/I_B≦6 A method for lighting a short arc discharge lamp, characterized by setting. (2) A lighting method in which a period of applying a high lighting current and a low lighting current is repeated, wherein the high lighting current supplies a base current I_B and a pulse current of a peak current value I_P with a pulse width t_P to the base current I_B. is repeatedly superimposed after the pulse pause period T and the base current I
The relationship between _B, the pulse width t_P, the peak current value I_B, and the pulse pause period T is 0.03≦t_P≦3 (ms) 0.1≦T≦10 (ms) 1.4≦I_P/I_B≦ 6, and the low lighting current value I_B' is I_B'/I_B' compared to the base current value I_B of the high lighting current.
A method for lighting a short arc discharge lamp characterized by satisfying the relationship B≧0.2.