JP4622998B2 - Excimer discharge lamp light source device - Google Patents

Description

  The present invention relates to the structure of a light source device for an excimer discharge lamp that performs dielectric barrier discharge.

  In recent years, a rare gas such as xenon is sealed inside a hermetic container made of a dielectric material, and a dielectric barrier discharge is performed in the sealed space by applying a high-frequency voltage between a pair of electrodes disposed between the dielectric materials. Thus, an excimer discharge lamp that temporarily changes xenon to an excimer state and emits ultraviolet rays when the energy level falls to the ground state is used as a light source for surface cleaning and surface modification of semiconductors and electronic components.

Patent Document 1 (Japanese Patent No. 3757790) discloses a light source device 100 ′ using a dielectric barrier discharge lamp (= excimer discharge lamp) as shown in FIG.
An excimer discharge lamp 10 ′ using synthetic quartz glass as a dielectric for the discharge vessel 11 ′ is used for optical cleaning of a liquid crystal glass substrate, surface modification of a plastic material, and the like. The lamp is mounted in a dedicated lamp house 20 ′, in which an excimer discharge lamp 10 ′ and a metal block 30 ′ for cooling the lamp are housed, and a light extraction window 40 ′ is provided on the irradiated object side. ing.
A water cooling pipe 31 ′ is embedded in the metal block 30 ′ as a cooling means, and cooling water flows to cool the metal block 30 ′. The reason why the lamp needs to be cooled is to suppress the UV transmittance of the discharge vessel 11 'from being lowered by the temperature rise, the temperature of the excimer-producing gas in the discharge vessel 11' is raised, and the excimer luminous efficiency is lowered. This is to suppress this.
The metal block 30 'has a flat or lamp-shaped groove 32', and the lamp 10 'is fixed so that the mesh electrode 12' on the outer wall of the discharge vessel 11 'is in contact with the metal block 30'. The lamp 10 'was cooled by the cooled metal block 30'. Reference numeral 16 'denotes an inner electrode.

However, in the excimer discharge lamp light source device of the type that uses such a metal block to cool the lamp, it has been found that there are some cases where cracks occur in the discharge vessel of the excimer discharge lamp by lighting for a long time exceeding 1000 hours. It was.
In particular, it has been found that cracks are likely to occur in an excimer discharge lamp having a discharge vessel length exceeding 800 mm.
Japanese Patent No. 3757790

The inventors diligently studied the cooling state of the lamp by the metal block.
Even when the lamp is brought into contact with the metal block via the electrode, the temperature of the portion in contact with the metal block is cooled until the electrode and the outer wall of the discharge vessel on the lower surface thereof are substantially equal to the temperature of the metal block. Specifically, it was found that it was cooled to about 100 ° C.

  On the other hand, it was found that the temperature of the outer wall of the discharge vessel on the side opposite to the metal block, which is not in contact with the metal block, reached a high temperature of about 300 to 350 ° C., depending on the input power. That is, a temperature difference of 200 deg or more has occurred between the “front” and “back” of the lamp.

This temperature difference is assumed to be a factor for shortening the lamp life as follows. FIG. 6 is a diagram schematically showing what force is applied to the lamp in the positional relationship with the metal block. FIG. 6A shows stress due to thermal expansion, and FIG. 6B shows stress due to accumulation of ultraviolet strain.
First, as shown in FIG. 6 (a), first, the difference in thermal expansion due to the temperature difference between the metal block side of the lamp and the lamp on the opposite side of the metal block side is the so-called “front” and “back”. Will occur. Specifically, for example, a lamp having a total length of 1 m causes an expansion difference of 0.2 mm to 0.3 mm. For this reason, on the side opposite to the metal block side, a tensile stress in the direction of bending the lamp (the direction of the arrow in FIG. 6A) is applied, and the discharge vessel portion on the side opposite to the metal block side cracks and breaks. It becomes easy. For long lamps longer than 1 m, this effect is even greater.

  Next, when the excimer discharge lamp is turned on, the emitted ultraviolet rays are irradiated to the discharge vessel, and therefore, ultraviolet distortions having different sizes are stored in the discharge vessel as indicated by arrows in FIG. In general, ultraviolet strain accumulated in quartz glass is accumulated more as the temperature is lower. Therefore, the accumulated amount of ultraviolet strain (residual stress) differs between the “front” and “back” of the lamp depending on the temperature. Accordingly, a large amount of ultraviolet distortion is accumulated in the discharge vessel portion on the metal block side, the stress balance of the entire discharge vessel is lost, and the lamp is easily damaged.

If the cooling block is not used, the above problem will be solved, but the lamp will be overheated (about 450 ° C or higher), the temperature of the gas in the discharge vessel will rise, the excimer luminous efficiency will decrease, and the discharge will Since the ultraviolet transmittance of the container is lowered, the light output is lowered. In addition, lamp components such as electrodes deteriorate due to high temperatures, resulting in a shortened lamp life.
Accordingly, an object of the present invention is to prevent the light output from being lowered by efficiently cooling the lamp, to suppress the deterioration of the lamp components without causing cracks in the discharge vessel, and to use the lamp for a long time. An object of the present invention is to provide a discharge lamp light source device.

  From the above, it has been concluded that the following means are necessary to provide a light source device that uses a metal block but does not cause defects such as cracks and reduced luminous efficiency in the lamp.

  A first means is a lamp in which an excimer generating gas is sealed in a discharge vessel made of a dielectric, an excimer discharge lamp having an electrode on the outer wall of the discharge vessel, and a metal block for cooling the excimer discharge lamp. An excimer discharge lamp light source device comprising a house and irradiating an object to be irradiated located on the side opposite to the metal block with light from the excimer discharge lamp. The excimer discharge lamp light source device is provided with a lamp support mechanism for supporting the outer wall and the electrode on the outer wall of the discharge vessel at a distance from the metal block.

  2. The second means according to claim 1, wherein the support mechanism includes a lamp base that holds a lamp at an end of the discharge vessel and a lamp holder that fixes the lamp base to the lamp house. An excimer discharge lamp light source device is provided.

  The third means is that the lamp base is formed with a lamp holding hole that is deviated from the center of the lamp base, and the excimer discharge lamp is inserted and fixed in the hole to thereby fix the outer wall of the discharge vessel and the lamp base. 3. The excimer discharge lamp light source device according to claim 2, wherein the electrode on the outer wall of the discharge vessel is held away from the metal block.

  According to a fourth means, the lamp holder includes a clamping part that sandwiches the lamp base, and a support part that leads to the lamp house and reaches the lamp house, and by appropriately setting the length of the support part. 3. The excimer discharge lamp light source device according to claim 2, wherein the discharge vessel outer wall and the electrode on the discharge vessel outer wall are held apart from the metal block.

  The fifth means is characterized in that the distance between the outer wall of the discharge vessel and the electrode on the outer wall of the discharge vessel is 0.5 to 1.5 mm away from the metal block. The excimer discharge lamp light source device described is used.

  According to the present invention, the temperature difference when the lamp is lit on the metal block side and the opposite side of the discharge vessel of the lamp can be alleviated, there is no problem of lamp overheating, and there is no crack in the discharge vessel. It is possible to provide an excimer discharge lamp light source device that can cool the lamp efficiently in order to increase the luminous efficiency of the lamp.

FIG. 1 is a configuration diagram of a light source device showing an embodiment of the present invention, and FIG. 1A is a cross-sectional view of the light source device in the tube axis direction of the lamp.
The excimer discharge lamp 10 has a lamp base 13 attached at both ends thereof, the lamp base 13 is supported by a lamp holder 14, and the lamp holder 14 is fixed to a lamp house 50.
In FIG. 1, electrodes on the outer wall of the discharge vessel are omitted.
FIG. 1B shows a cross-sectional view taken along the line C-C in FIG. 1A, and a water cooling pipe 31 is disposed in the metal block 30, and cooling water flows therethrough. A groove portion 32 is formed in the metal block 30, and the excimer discharge lamp 10 is disposed with respect to the metal block 30 so as to be separated from the entire length. The metal block 30 is made of aluminum or copper. In addition, the groove part 32 of the metal block 30 is not essential, and the surface on the lamp side may be a flat shape without a groove depending on the lamp shape.

A lamp support mechanism for supporting the discharge vessel outer wall and the electrode on the discharge vessel outer wall away from the metal block, a lamp base for holding the lamp at the end of the discharge vessel, and a lamp holder for fixing the lamp base to the lamp house; Consists of.
FIG. 1 (c) shows a DD cross-sectional view of FIG. 1 (a). The lamp base 13 is formed with a lamp holding hole 13a offset from the center of the lamp base 13, and the hole The excimer discharge lamp 10 is inserted and fixed to the discharge vessel 11 and the electrodes on the discharge vessel outer wall are held away from the metal block 30.

  The fact that the lamp holding hole 13a is formed by being deviated from the center of the lamp base 13 means the following. FIG. 9 is a view for explaining the lamp holding hole of the lamp base, and is a view of the lamp base as seen from a plane perpendicular to the lamp tube axis. 9A, 9B, and 9C show examples of lamp base shapes. In the figure, the dotted circle inside the outer shell indicates the position of the conventional lamp holding hole opened at the center of the lamp base, and the solid circle inside the outer shell is offset from the center of the lamp base. The position of 13a is shown. FIG. 9A shows a state where the center of the lamp holding hole is shifted from the position A to the position B and is biased.

  Further, as shown in FIG. 1C, the lamp holder 14 includes a sandwiching portion 14a that sandwiches the lamp base 13 and a support portion 14b that leads to the sandwiching portion and reaches the lamp house. By appropriately setting the length of the portion 14b, the outer wall of the discharge vessel 11 and the electrode on the outer wall of the discharge vessel can be held away from the metal block 30.

  The lamp base and the lamp holder may not be separated, and the lamp base portion for inserting and holding the lamp end portion and the lamp holder portion for fixing the lamp base portion to the lamp house may be integrated.

FIG. 2 is a first embodiment showing a specific configuration of an excimer discharge lamp applied to the present invention, and an outer tube 11a and an inner tube 11b whose outer shapes are substantially cylindrical are arranged coaxially, A discharge vessel 11 having a hollow cylindrical discharge space closed at both ends between the two tubes is provided. The discharge vessel is filled with an excimer-generating gas, and at least a part of the discharge vessel 11 is made of metal inside the inner tube 11b. An inner electrode 16 is provided, and a conductive mesh electrode 12 as an outer electrode is provided on the outer wall of the outer tube 11a. 2A is a cross-sectional view along the tube axis, and FIG. 2B is a cross-sectional view along AA.
In this example, the lamp base 13 is formed with a lamp holding hole 13a offset from the center of the lamp base 13, and the excimer discharge lamp is inserted and fixed in the hole 13a to fix the metal block. On the other hand (not shown), the lamp is spaced apart from both the electrode and the discharge vessel over the entire length. In FIG. 2, the cross section of the lamp base 13 shows a state in which the upper part of the lamp base 13 is thicker than the lower part when viewed in the direction perpendicular to the tube axis on the paper surface.

  FIG. 3 shows a second embodiment in which the inner electrode 16 of the pair of electrodes is disposed in the inner tube 17 at the center of the discharge vessel 11, and the other outer electrode 22 is coiled on the outer wall of the discharge vessel. It is arranged by winding. In the figure, reference numeral 18 denotes a support that supports the inner tube.

  FIG. 4 shows a third embodiment, which is an excimer discharge lamp 10 having a rectangular discharge vessel 11, and a pair of electrodes 22 and 22 are disposed on the outer wall of the discharge vessel. 4A is a cross-sectional view along the tube axis, and FIG. 4B is a cross-sectional view taken along the line BB in FIG. 4A.

  Next, the table of FIG. 5 shows the results of examining the change in lamp temperature by changing the distance between the metal block and the lamp. The temperature-measured lamp is an excimer discharge lamp having a double tube structure in which the inner tube and the outer tube shown in FIG. 2 are arranged coaxially and sealed at both ends. The overall length is 1400 mm, the outer diameter of the outer tube is 42 mm, It has a thickness of 2.5 mm, an outer diameter of the inner tube of 14 mm, and a wall thickness of 1 mm, and encloses xenon gas as an excimer generating gas. The input power is 1 kW. The distance between the metal block and the lamp was measured by measuring the distance between the external electrode immediately above the radial center of the lamp and the metal block immediately above the external electrode.

The lamp was turned on for 50 seconds and turned off for 10 seconds 30 times, and the surface temperature of the discharge vessel was measured with a thermocouple. The temperature measurement part is a central part in the longitudinal direction of the lamp.
According to this result, when the distance between the electrode outside the discharge vessel and the metal block is 0.5 to 1.5 mm, the temperature of the discharge vessel on the metal block side and the temperature of the discharge vessel on the opposite side of the metal block The difference (discharge vessel temperature difference) is 11 deg or less, and there is almost no temperature difference.
If there is no discharge vessel temperature difference, an excimer discharge lamp light source device can be provided that does not cause cracks due to differences in the thermal expansion difference of the discharge vessel and the difference in the accumulated amount of ultraviolet distortion.

  If the distance between the electrode outside the discharge vessel and the metal block exceeds 5 mm, the temperature of the discharge vessel on the metal block side reaches 400 ° C., the cooling effect is weak, the excimer luminous efficiency is lowered, and the lamp components are deteriorated. The discharge vessel temperature difference becomes 60 deg, and the metal block for cooling does not contribute to the cooling of the lamp at all.

  The discharge vessel temperature difference varies depending on the lamp input power, the cooling water flow rate, and the discharge vessel shape. However, the idea of separating the metal block and the discharge vessel including the external electrode portion is a common technical idea. And in industrial applications, the input power of the lamp used in the excimer discharge lamp is about 1 kW, the flow rate of cooling water is about 5 L / min, and the result is equivalent to the temperature measurement result of the present invention. It is guessed.

  FIG. 8 is a diagram showing another embodiment of the light source device of the present invention. The lamp base and base holder are not used, and the lamp support mechanism is a holding metal fitting 60 that holds the discharge vessel at a plurality of locations, and the holding metal fitting holds the lamp in accordance with the outer peripheral shape of the lamp. It consists of a portion 60a and a support portion 60b that is connected to the sandwiching portion 60a and is inserted through an opening provided in the metal block and fixed at the opening outlet. Fig.8 (a) is sectional drawing along a pipe axis, FIG.8 (b) is EE sectional drawing. As can be seen from FIG. 8B, the metal block 30 and the holding metal 60 are in contact only at the support portion 60b.

It is a block diagram of the light source device which shows embodiment of this invention. It is a figure of the 1st Example of the excimer discharge lamp applied to this invention. It is a figure of the 2nd Example of the excimer discharge lamp applied to this invention. It is a figure of the 3rd Example of the excimer discharge lamp applied to this invention. It is a table | surface which shows the relationship of the change of lamp temperature regarding the separation distance of a metal block and a lamp. It is the figure which showed typically what kind of force is applied to the lamp | ramp in the positional relationship with a metal block. It is a figure of the conventional light source device. It is a figure which shows other embodiment of the light source device of this invention. It is a figure explaining the lamp | ramp holding hole of the lamp base applied to this invention.

Explanation of symbols

10, 10 'excimer discharge lamp 11, 11' discharge vessel 12, 12 'mesh electrode 13 lamp base 13a lamp holding hole 14 lamp holder 14a clamping portion 14b support portion 16, 16' inner electrode 17 inner tube 18 support for supporting the inner tube Body 20 'Lamp house 22 Outer electrode 30, 30' Metal block 31, 31 'Water cooling pipe 32, 32' Groove 40 Light extraction window 50 Lamp house 60 Holding bracket 60a Holding part 60b Supporting part 100, 100 'Light source device

Claims (1)

An excimer-generating gas is sealed in a discharge vessel made of a dielectric, and an excimer discharge lamp having an electrode on the outer wall of the discharge vessel and a metal block for cooling the excimer discharge lamp are provided. In an excimer discharge lamp light source device for irradiating an object to be irradiated located on the side opposite to the metal block with light from the discharge lamp,
A lamp support mechanism for supporting a discharge vessel outer wall and an electrode on the discharge vessel outer wall spaced apart from the metal block over substantially the entire length of the discharge vessel of the excimer discharge lamp;
The support mechanism comprises a lamp base that holds a lamp at the end of the discharge vessel, and a lamp holder that fixes the lamp base to the lamp house,
The excimer discharge lamp light source device characterized in that the lamp holder includes a sandwiching part that sandwiches the lamp base and a support part that leads to the sandwiching part and reaches the lamp house .

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