JPH0589835A - Ultraviolet ray source and ultraviolet irradiation device - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the self-absorption of ultraviolet rays and increase the output of ultraviolet rays. [Structure] Each arc tube portion 4 of a substantially U-shaped arc tube 2 has a flat cross section, and the plane surfaces 5 of each arc tube portion 4 are inclined so as to face each other. [Effect] The discharge space in the arc tube 2 becomes flat, the thickness of the mercury vapor layer is reduced, and the self-absorption of ultraviolet rays by the mercury vapor layer is suppressed. Ultraviolet rays are irradiated from the wide light emitting surface of each flat surface 5 to substantially the same place on the irradiation surface, and the amount of ultraviolet rays on the irradiation surface is increased, so that the ultraviolet intensity is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet light source and an ultraviolet irradiation device used for an ultraviolet photochemical reaction.

[0002]

2. Description of the Related Art In this type of ultraviolet light source, electrodes are sealed at both ends of an arc tube made of quartz glass or the like which transmits ultraviolet rays, and mercury and rare gas are sealed in the arc tube.
It comprises a low-pressure mercury discharge lamp which emits ultraviolet rays mainly having resonance lines of 185 nm and 254 nm of mercury by ionizing and exciting mercury atoms by generating discharge in the arc tube by energizing the electrodes.

The ultraviolet light source is, for example, a light CV.
D (Chemical Vapor Deposition)
n) method, used for semiconductor manufacturing such as synthesis of Si thin film, photo-curing and photo-ashing of resist, photo-cleaning, etc., and also for water purification, sterilization treatment, meat sterilization treatment, etc. It is used.

By the way, recently, there has been a demand for high-speed photochemical treatment as described above, and improvement in the output of ultraviolet rays emitted from an ultraviolet light source is required.

A conventional ultraviolet light source has an arc input of 5 W /
The lamp capacity is about 500 W. In this case, the arc tube has a circular cross section with an inner diameter of approximately 24 mm (cross sectional area =
It had a straight tube shape or a substantially U-shape at about 4.5 cm ² ) and had a discharge current of 7 A (current density 1.6 A / cm ² ).

[0006]

In such an ultraviolet light source, in order to improve the ultraviolet light output, it is necessary to increase the discharge current. In the conventional case, as shown by the characteristic A shown by the broken line in FIG. When the density is 1.6 A / cm ² or less, the lamp input increases and the ultraviolet ray output increases as the discharge current increases, but the output reaches the maximum in the current density range of 1.6 to ² A / cm ^2. Reaches saturation, and further 2A / cm
Above ² , the UV output drops despite increasing lamp input.

The cause of this is not clear, but when the current flowing in the discharge path is increased, the current density in the arc is increased, and the vaporized mercury atoms are excessively ionized, and as a result, the excited atoms that contribute to light emission. It is considered that there is a shortage.

To compensate for the amount of excited atoms, it is necessary to increase the mercury vapor pressure.
Self-absorption of 54 nm ultraviolet rays occurred, and it was generated 2
It is widely known that 54 nm ultraviolet rays are absorbed by mercury vapor in the arc and the ultraviolet ray output decreases.

The present invention has been made in view of the above circumstances, and provides an ultraviolet light source which has a small self-absorption effect of ultraviolet light and can increase the ultraviolet light output, and an ultraviolet irradiation device using the ultraviolet light source. The purpose is that.

[0010]

According to a first aspect of the present invention, a plurality of arc tube portions having a flat cross section are provided, and the flat surfaces of the arc tube portions are inclined so as to face each other.

According to a second aspect of the present invention, in the first aspect of the invention, electrodes are sealed at both ends of the arc tube, and mercury and a noble gas are enclosed in the arc tube so that the current density is 1 to 6 A /.
It is intended to light in the range of cm ² .

According to a third aspect of the present invention, in the first or second aspect of the invention, the vapor pressure of mercury sealed in the arc tube is 0.7 to 13 Pa at room temperature, and the rare gas sealing pressure is 1 at room temperature.
It is set to 3 to 133 Pa.

According to a fourth aspect of the present invention, there are provided a plurality of arc tube portions each having a flat cross section and a light source section in which the plane surfaces of each arc tube portion are inclined so as to face each other, and the plane surfaces of each arc tube portion are inclined. Is provided with an irradiating section for irradiating ultraviolet rays downward with the surface sides inclined opposite to each other as a lower surface, and a supply means for supplying an object to be irradiated below this irradiating section.

[0014]

According to the invention of claim 1, since the arc tube portion of the arc tube has a flat cross section, the discharge space also has a flat shape and the thickness of the mercury vapor layer is reduced, that is, the mercury vapor layer self-absorbs ultraviolet rays. Therefore, even if the current density is increased to a range that is conventionally considered to exceed the saturation region, the ultraviolet ray output is improved. Moreover, the flat surfaces of the arc tube portions of the arc tube are inclined so as to face substantially the same place on the irradiation surface,
Ultraviolet rays are irradiated from the wide light emitting surface of each flat surface to substantially the same place on the irradiation surface, so that the amount of ultraviolet rays increases and the intensity of ultraviolet rays improves.

According to the second aspect of the present invention, in the first aspect of the invention, since the self-absorption of ultraviolet rays by the mercury vapor layer is suppressed, the saturation range of 1 to 6A, which is conventionally considered to exceed the saturation region, is used.
Even when the current density is increased up to the range of / cm ² , the UV output is improved.

According to the invention of claim 3, in the invention of claim 1 or 2, since the self-absorption of ultraviolet rays by the mercury vapor layer is suppressed, conventionally, the self-absorption of ultraviolet rays is 0.7 to 0.7 at room temperature. The vapor pressure of mercury can be increased to the range of 13 Pa, and the filling pressure of the rare gas can be increased to the range of 13 to 133 Pa at room temperature, so that the ultraviolet ray output is improved.

According to a fourth aspect of the present invention, the object to be irradiated is supplied below the light source section whose lower surface is the surface side where the planes of the plurality of arc tube sections are inclined so as to oppose each other, and the ultraviolet irradiation processing is performed at high speed. Can be applied.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 is an ultraviolet light source composed of a low-pressure mercury discharge lamp, and this ultraviolet light source 1 is
The arc tube 2 is made of synthetic quartz and has a substantially U shape.

The arc tube 2 has a flat quadrangular cross section, is composed of a bent portion 3 and a pair of arc tube portions 4 arranged in parallel, and each arc tube portion 4 has a short side x and a long side y. Ratio x / y is about 0.2 to 0.8, and the flat surfaces 5 on the lower surfaces of both arc tube portions 4 are inclined so as to face each other. In this embodiment, the short side x is 15 mm, the long side y is 30 mm, and the cross-sectional area is about 4.5 cm ² as in the conventional case.

A stem 6 is sealed at both ends of the arc tube 2, and an anode 7 and a hot cathode 8 are supported on the stem 6. Each anode 7 is disposed in front of the hot cathode 8 in the discharge space, the anode 7 is formed by a circular coil, a cylinder or an annular plate, and the hot cathode 8 is formed by a filament coil.

The arc tube 2 is filled with a rare gas such as mercury and argon. The vapor pressure of this mercury is 0.
7 ~ 13Pa, Argon gas filling pressure is 13 ~ during lighting.
It is enclosed so as to be 133 Pa.

The ultraviolet light source 1 is connected to an AC power source via a lighting circuit device 11. The lighting circuit device 11 has, for example, a step-up transformer 12 and a heater transformer 13, the step-up transformer 12 is connected to the anode 7, and the heater transformer 13 is connected to the hot cathode 8. Therefore, the hot cathode 8 always generates heat and emits thermoelectrons. In addition, 14
Is a diode.

The lighting circuit device 11 is adapted to supply an input power of 500 W to the ultraviolet light source 1 from, for example, a commercial power source, whereby a discharge current of 7 A flows in the ultraviolet light source 1 during discharging, and the current density is increased. Is 1.6 to 6 A / cm ² .

The peak value of the discharge current is set to 1.2 times or less of its effective value. This is because the UV light source that is turned on at a high current density of 1 A / cm ² or more increases the UV output when the peak value of the discharge current is 1.2 times or less the effective value. Is confirmed by the present inventors.

In the ultraviolet light source 1 configured as described above, when 500 W of power is applied from the power source through the lighting circuit device 11, the hot cathode 8 is connected to the AC power source through the heater transformer 13. The hot cathodes 8 always generate heat and emit thermoelectrons. Then, power is applied from the step-up transformer 12 between the anode 7 and the hot cathode 8.

Therefore, in the ultraviolet light source 1, a half-wave current flows between the anode 7 on the one end side and the hot cathode 8 on the other end side, discharge is generated between them, and then the hot cathode 8 on the one end side A reverse half-wave current flows between the anode 7 on the other end side and discharge occurs between them. Thus, each time the polarity is reversed, the anodes 7 and the hot cathodes 8 alternately discharge and continue lighting.

Such discharge excites mercury-based vapor, which causes the mercury resonance lines 185 nm and 254.
Light in the short wavelength ultraviolet region including nm is emitted.

As shown in FIG. 3 (a), the ultraviolet light source 1 is inclined so that the planes 5 of the arc tube portions 4 of the arc tube 2 face each other at substantially the same position on the irradiation surface. The ultraviolet light is irradiated from the wide light emitting surface of each flat surface 5 to the substantially same place on the irradiation surface, so that the amount of the ultraviolet light is increased and the ultraviolet light intensity is improved. In addition, FIG. 3 (b) shows the case of the arc tube portion 4a having a circular cross section,
In this case, the ultraviolet intensity is low, and FIG. 3 (c) shows the case where the flat surface 5b is parallel to the irradiation surface by the arc tube portion 4b having a flat cross section. As a result, the ultraviolet intensity is slightly improved, but the ultraviolet intensity between the arc tube portions 4b is reduced.

Further, since the arc tube 4 of the arc tube 2 has a flat cross section, the discharge space also has a flat square, and the thickness of the mercury vapor layer is reduced. Therefore, since the ultraviolet ray self-absorption by the mercury vapor layer is small, it is possible to increase the current density and increase the ultraviolet ray output. In other words, when the current flowing in the discharge path is increased to increase the current density in the arc more than in the past, the vaporized mercury atoms are excessively ionized,
For this reason, the number of excited atoms contributing to light emission is insufficient, but the mercury vapor pressure increases as the current density increases, and the mercury atomic amount is compensated for, so that excitation is actively promoted and 185
The UV output at nm and 254 nm is increased.

The above results are confirmed by experiments, and the characteristic B shown by the solid line in FIG. 4 is the case of the above embodiment. In this characteristic B, the current density is 1.6 cm ² to 6 A /
Up to cm ^2, the lamp input increases with increasing discharge current,
UV output increases.

Therefore, it is confirmed that the current density is increased and the ultraviolet ray output is significantly improved as compared with the conventional characteristic A.

Next, an embodiment of an ultraviolet irradiation device using the ultraviolet light source 1 will be described with reference to FIGS. 5 and 6.

In FIG. 5, an irradiation section 22 is provided in the upper upper area of the machine body 21, and a supply means 24 for supplying an irradiation object is provided to a processing section 23 below the irradiation section 22.

An irradiation unit 25 is arranged in the irradiation unit 22. As shown in FIG. 6, in the irradiation unit 25, the electrode portion of the ultraviolet light source 1 is supported and the bent portion 3 is supported by the holder 27 in a unit frame 26 having an opening at the bottom. A reflection plate 28 is arranged so as to face the upper surface. A fan 29 and a motor 30 for driving the fan 29 are arranged at the right end of the unit frame 26.

The supply means 23 has a drawer body 31 which is drawn out to the front surface of the machine body 21. The bottom plate 32 of the drawer 31 is a machine body.
The roller 34 is mounted on the roller 33 on the 21 side, and the roller 34 provided on the bottom plate 32 is fitted to the rail 35 on the machine body 21 side so that it can be pulled out and stored in the front-rear direction. A moving table 37 for setting an object to be irradiated is provided on a rail 36 provided on a side plate protruding upward from both sides of the bottom plate 32 so as to be movable in parallel by a roller 38, and is driven in the front-rear direction by a driving means (not shown). To be done.

An operating section 39 is provided on the front surface of the machine body 21.

Then, the drawer body 31 is pulled out from the machine body 21, the object to be irradiated is set on the moving table 37, and the drawer body 31 is housed in the machine body 21.

By moving the moving table 37, the object to be irradiated is moved below the ultraviolet light source 1 which is turned on, and the object to be irradiated is irradiated with ultraviolet rays. At this time, as described above, since the ultraviolet ray intensity and the ultraviolet ray output are high, the ultraviolet ray irradiation process is performed at a high speed.

The ultraviolet irradiation device is not limited to the configuration of this embodiment, and may be, for example, a case where the object to be irradiated is continuously carried in and out below the ultraviolet light source 1 by the supply means 24.

Further, a plurality of ultraviolet light sources having arc tube portions having a flat cross section may be arranged in parallel and the light source portions may be formed by inclining the flat surfaces of the arc tube portions of adjacent ultraviolet light sources so as to face each other. ..

[0042]

According to the first aspect of the invention, since the arc tube portion of the arc tube has a flat cross section, the discharge space also has a flat shape, and the thickness of the mercury vapor layer is reduced. Since the self-absorption of ultraviolet rays is suppressed, the ultraviolet ray output can be improved even when the current density is increased to the range that is conventionally considered to exceed the saturation region. Moreover, since the flat surfaces of the arc tube portions of the arc tube are inclined so as to face substantially the same place on the irradiation surface, ultraviolet rays are irradiated from the wide light emitting surface of each flat surface to the substantially same position on the irradiation surface. The amount of ultraviolet rays on the irradiated surface is increased, and the ultraviolet intensity can be improved.

According to the invention of claim 2, in the invention of claim 1, since the self-absorption of ultraviolet rays by the mercury vapor layer is suppressed, it is conventionally considered that the saturation region is exceeded.
Even when the current density is increased up to the range of 6 A / cm ² , the ultraviolet ray output can be improved.

According to the invention of claim 3, in the invention of claim 1 or 2, self-absorption of ultraviolet rays by the mercury vapor layer is suppressed. The vapor pressure of mercury can be increased to the range of 7 to 13 Pa, and the pressure of the rare gas enclosed can be increased to the range of 13 to 133 Pa at room temperature to improve the ultraviolet light output.

According to the invention of claim 4, the object to be irradiated is supplied by the supplying means below the light source section whose lower surface is the surface side in which the planes of the plurality of arc tube sections are inclined so as to face each other. UV irradiation treatment can be performed.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of an ultraviolet light source of the present invention.

FIG. 2 is a configuration diagram showing the ultraviolet light source and a lighting circuit device.

FIG. 3 is a characteristic diagram showing an ultraviolet intensity distribution, in which (a) shows this example and (b) and (c) show comparative examples.

FIG. 4 is a characteristic diagram of ultraviolet ray output.

FIG. 5 is a front view in which a part of the ultraviolet irradiation device is cut away.

FIG. 6 is a sectional view of the irradiation unit.

[Explanation of symbols]

 1 ultraviolet light source 2 arc tube 4 arc tube section 5 flat surface 22 irradiation section 24 supply means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01J 61/72 7135-5E // H01L 21/205 7454-4M

Claims (4)

[Claims] 1. An ultraviolet light source comprising a plurality of arc tube portions each having a flat cross section, wherein the plane surfaces of each arc tube portion are inclined so as to face each other. 2. An electrode is sealed at both ends of the arc tube, and mercury and a rare gas are sealed in the arc tube, and the lamp is lit in a current density range of 1 to 6 A / cm ^2. The ultraviolet light source described. 3. The vapor pressure of mercury sealed in the arc tube is 0.7 to 13 Pa at room temperature, and the sealing pressure of the rare gas is 13 to 13 Pa at room temperature.
It was 133 Pa, The ultraviolet light source of Claim 1 or Claim 2 characterized by the above-mentioned. 4. A light source section having a plurality of arc tube sections having flat cross sections and having inclined planes of the arc tube sections facing each other, wherein the flat planes of the arc tube sections are opposed to each other. An ultraviolet irradiation device comprising: an irradiation unit that irradiates ultraviolet rays downward with the inclined surface side as a lower surface; and a supply unit that supplies an object to be irradiated below the irradiation unit.