JP2010129442A - Metal halide lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress blackening around an electrode in lighting of a water-cooled metal halide lamp. <P>SOLUTION: A pair of discharge electrodes 121 and 122 are oppositely disposed in the axial direction within an airtight container 11 provided with a discharge space 10, which is made of ultraviolet transmitting quartz glass and has airtightness. A proper amount of a sealing material composed of iron and halogen for emitting ultraviolet light is sealed together with sufficient amounts of rare gas and mercury for maintaining an arc-discharged state in the discharge space 10. The sealing amount M (mg/cc) of iron as the sealing material is set to a value which satisfies the relation of 0.001<M<0.15 relative to the capacity of the discharge space 10 when the lamp input per unit length is 50-160 W/cm. According to this structure, the amount of iron per volume of the discharge space 10 is limited, whereby the blackening around the electrode in the water-cooled metal halide lamp can be suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a metal halide lamp which is used for curing a paint or photoreaction of a functional polymer film by irradiating ultraviolet rays, and is particularly suitable for a water-cooled type.

A conventional ultraviolet irradiation lamp in which electrodes are sealed at both ends of a discharge space is held in a double-tube type water cooling jacket composed of an inner tube and an outer tube. In the discharge space, at least one of metal halides such as iron, tin and thallium is added together with mercury and a rare gas. Then, arc discharge is performed in mercury vapor at about 1 to 10 atm, and a light emission in a wide long wavelength region is realized by enclosing a metal compound. (For example, Patent Document 1)
JP-A-8-148121

  The technique disclosed in Patent Document 1 is a so-called long arc Fe (iron) metal halide lamp having a distance between electrodes of 1000 mm or more. This metal halide lamp needs to be cooled in order to extend the lamp life, and a water-cooled type is used for reliable cooling. In the case of the water-cooled type, it is necessary to apply a protective film to the outer surface of the discharge space around the electrode of the lamp so as not to lower the temperature of the electrode. Since it gets dirty, it cannot be applied.

  For this reason, the enclosed iron is alloyed with tungsten, which is the main component of the electrode, to have a low melting point, and as the amount of iron alloy with tungsten increases, the iron during lighting erodes the quartz glass and becomes blackened. Is likely to occur. There is a problem that blackening becomes more remarkable because the amount of iron enclosed needs to be increased as the light emission length is increased.

  An object of the present invention is to provide a metal halide lamp capable of suppressing blackening around the electrode even when the tungsten electrode and the amount of iron enclosed in the discharge space are limited to be turned on by a water cooling method. .

  In order to solve the above-described problems, a metal halide lamp according to the present invention includes an airtight container in which a discharge space having airtightness is formed using an ultraviolet light transmissive material, and is sealed in the airtight container and disposed opposite to the discharge space. A pair of refractory metal discharge electrodes, and an enclosure made of iron and halogen together with a rare gas and mercury in an amount sufficient to maintain an arc discharge in the discharge space. The enclosed amount M (mg / cc) of iron is characterized by a relationship of 0.001 <M <0.15 with respect to the volume of the discharge space.

  According to this invention, by limiting the amount of iron per volume of the discharge space, alloying of iron and tungsten electrodes can be suppressed, and as a result, blackening can be suppressed even in the case of a water-cooled metal halide lamp. It becomes.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  1 to 3 are diagrams for explaining an embodiment of a metal halide lamp according to the present invention. FIG. 1 is a basic structural view, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. FIG.

  In FIG. 1, electrodes 121 and 122 made of, for example, a tungsten material are disposed at intervals inside the hermetic vessel 11 made of quartz glass having ultraviolet transparency and having a discharge space 10 formed therein. The The hermetic container 11 is composed of a single tube having an outer diameter φ of 27.5 mm, a wall thickness m of 2.25 mm, and a light emission length L of 2000 mm, for example.

  The electrodes 121 and 122 are welded to one end of the molybdenum foils 141 and 142 via the inner leads 131 and 132, respectively. One end of an outer lead (not shown) is welded to the other end of the molybdenum foils 141 and 142. The portions of the molybdenum foils 141 and 142 heat and seal the hermetic container 11 from the inner leads 131 and 132 of the hermetic container 11 to one end of the outer lead.

  The molybdenum foils 141 and 142 may be made of any material that has a thermal expansion coefficient close to that of quartz glass forming the hermetic container 11, but general molybdenum is used as a material suitable for this condition.

  The outer leads connected at one end to the molybdenum foils 141 and 142 are provided with lead wires 161 and 162 for feeding, which are electrically connected inside the sockets 151 and 152 made of heat-resistant and insulating material, for example. It is insulated and sealed and connected to a power supply circuit (not shown).

  In the airtight container 11, a sufficient amount of argon gas, which is a rare gas for maintaining arc discharge as an enclosure, is 1.3 kPa, and mercury and iron, mercury iodide, which are metals for emitting ultraviolet light. Tin is enclosed.

  The metal for emitting ultraviolet light may be mercury bromide instead of mercury iodide or thallium instead of tin. It does not matter if at least two of iron, tin, indium, bismuth, thallium, and manganese are enclosed.

  As shown in FIG. 2, a protrusion 17 having a steeple or rounded tip is integrally formed on the outer surface of the discharge vessel 11 between the electrodes 121 and 122. Although at least one protrusion 17 may be provided in the circumferential direction of the discharge vessel 11, a plurality of protrusions 17 may be formed as shown in FIG. The protrusion 17 is at least in a lower position in the attached state. When a plurality of protrusions 17 are formed, they may not necessarily be on the same lap but may be at a position shifted from the same lap. Further, the protrusion 17 is formed at least at one place in the longitudinal direction of the discharge vessel 11. In the case of a plurality of places, it may not be on the same line in the axial direction.

  The protrusions 17 are distinguished from exhaust pipe traces, which are also referred to as chips for enclosing inclusions such as rare gases in the discharge vessel 11. The height of the projection 17 provided from the outer peripheral surface of the discharge vessel 11 is higher than the exhaust pipe trace. Note that the exhaust pipe trace is not necessarily required by using the portion to be sealed of the discharge vessel 11 and can be eliminated.

  The height of the protrusion 17 is not particularly defined because it is determined by the positional relationship with the cooling mechanism of the water cooling of the lamp, but considering that it does not contact the cooling mechanism and does not affect other characteristics, it is 1 to 3 mm. The degree is preferred.

  The metal halide lamp configured in this manner is an ultraviolet ray having a high emission intensity around 365 nm when a lamp voltage of 2300 V, a lamp current of 10.3 A, and a potential gradient D of 11.5 V / cm are supplied to the electrodes 121 and 122. Can be emitted.

  FIG. 4 is a graph showing the relationship between the melting point temperatures of alloys having different iron (Fe) content with respect to tungsten (W).

That is, the melting point temperature of W before being alloyed with iron is 3410 ° C., whereas the melting point temperature of FeW (W, Fe alloy, Fe small) is 1216 ° C., Fe ₂ W (W, Fe alloy, In the case of Fe content, the temperature is 1016 ° C., about 1/3 of the melting point temperature of tungsten alone. Therefore, when the melting point temperature is lowered, alloying with an increased iron content proceeds, and the blackening phenomenon near the electrode due to the iron component is accelerated.

  FIG. 5 shows that when the lamp input per unit length is 50 to 160 W / cm, the amount M (mg / cc) of iron filled in the discharge space volume is changed in five steps from 0.001 to 0.2. It is explanatory drawing for demonstrating the result of having experimented about the blackening in a case, and the ultraviolet-ray intensity in 365 nm vicinity.

  As is apparent from FIG. 5, when the amount of iron enclosed M (mg / cc) is 0.001, blackening does not occur, but the intensity of ultraviolet light is less than the standard. When the amount of iron enclosed M (mg / cc) is 0.002, 0.003, and 0.15, blackening does not occur, and the ultraviolet light intensity satisfies the standard. When the amount M (mg / cc) of iron was 0.20, blackening occurred and the intensity of ultraviolet light did not reach the standard.

  For this reason, when the amount M (mg / cc) of iron enclosed in the discharge space volume is set to 0.20, iron accumulates around the electrode, which is the coldest part of the lamp during lamp cooling, and blackening occurs. Blackening can be prevented by setting the amount of enclosed iron M (mg / cc) to the discharge space volume to 0.15.

  As described with reference to FIG. 4, the amount of iron alloy at the tungsten electrode increases as the amount M (mg / cc) of iron enclosed with respect to the discharge space volume increases. Along with this, the melting point temperature of the electrode is lowered, and blackening occurs due to the erosion of the iron vaporized in the hermetic container 11 near the electrode during lighting.

  For this reason, the intensity of the emitted ultraviolet rays is secured by preventing the blackening phenomenon in the vicinity of the electrodes 121 and 122 of the airtight container 11 by limiting the amount M (mg / cc) of iron enclosed. be able to.

  In this way, when the lamp input per unit length is 50 to 160 W / cm, blackening can be suppressed by setting the relationship of 0.001 <M <0.15 to the discharge space volume. It becomes. In other words, the suppression of blackening suppresses a decrease in the intensity of ultraviolet rays, which contributes to a longer lamp life.

  FIGS. 6 and 7 are diagrams for explaining an embodiment in which the metal halide lamp of the present invention is used in an ultraviolet irradiation apparatus having a water-cooling type cooling mechanism. FIG. 6 is a system configuration diagram, and FIG. It is IIa-IIb sectional view taken on the line.

  The ultraviolet irradiation device includes a metal halide lamp 100 and a water cooling unit 200. The metal halide lamp 100 and the water cooling unit 200 are positioned at predetermined intervals by spacers 25a and 25b attached to the sockets 151 and 152 of the metal halide lamp 100.

  The water cooling unit 200 is formed of a transparent material such as cylindrical quartz glass, and includes an inner tube 21 and an outer tube 22 provided outside thereof, and has a double tube structure. The metal halide lamp 100 is included in the inner tube 21.

  In the water cooling unit 200, a coolant 24 such as water is circulated from the outside through connection pipes 23a and 23b provided at outer peripheral ends. As shown in FIG. 7, the coolant 24 has a low temperature from the connecting tube 23a, cools the metal halide lamp 100 from the connecting tube 23b, and discharges the warmed coolant 24. The water discharged by the metal halide lamp 100 in the process of passing between the inner tube 21 and the outer tube 22 is cooled and input again from the connection tube 23a, for example, and the coolant 24 is reused.

A metal oxide film containing a metal oxide is deposited on the outer surface of the outer tube 22. Examples of the metal oxide include titanium oxide (TiO ₂ ), cesium oxide (CeO ₂ ), zinc oxide (ZnO ₂ ), tin oxide (SnO ₂ ), and zirconium oxide (ZrO ₂ ). It is composed of at least one kind. The metal oxide film is component-adjusted so as to absorb a wavelength component of 300 nm or less in the light emitted from the metal halide lamp 100.

  When ultraviolet light is emitted from the metal halide lamp 100, the metal oxide film deposited on the outer surface of the outer tube 22 absorbs a wavelength component of 300 nm or less. Accordingly, ultraviolet light having a wavelength range of 300 to 430 nm effective for curing the resin is transmitted through the water cooling unit 200 and irradiated to an irradiation object such as a resin.

  Now, let us consider a case where the metal halide lamp 100 in which the diameter of the inner tube 21 of the water cooling unit 200 is 32 mm and the diameter of the outer tube 22 is 36 mm is constant power in the water cooling unit 200.

  Since the metal halide lamp used here can suppress blackening even if it is a water-cooled type, the life of the lamp can be extended and the maintainability of the ultraviolet irradiation device can be improved.

The basic structure figure for demonstrating one Embodiment regarding the metal halide lamp of this invention. The enlarged view of the principal part of FIG. FIG. 2 is a sectional view taken along line Ia-Ib in FIG. 1. Explanatory drawing for demonstrating the relationship with melting | fusing point temperature in the state of the amount of iron alloys with respect to tungsten. Explanatory drawing for demonstrating the relationship of the blackening frequency by the content of iron, and the influence of specific wavelength intensity. The system block diagram for demonstrating the Example at the time of using the metal halide lamp of this invention for the ultraviolet irradiation apparatus provided with the water-cooling type cooling mechanism. IIb-IIb sectional view taken on the line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Discharge space 11 Airtight container 121,122 Electrode 131,132 Inner lead 141,142 Molybdenum foil 151,152 Socket 161,162 Lead wire 17 Protrusion 100 Metal haloid lamp 200 Water cooling unit 21 Inner tube 22 Outer tube 23a, 23b Connection tube 24 Coolant 25a, 25b Spacer

Claims (5)

An airtight container in which a discharge space having airtightness is formed of an ultraviolet light transmissive material;
A pair of refractory metal discharge electrodes sealed in the hermetic container and disposed opposite to the discharge space;
A sufficient amount of rare gas to maintain arc discharge in the discharge space, mercury, and an inclusion made of iron and halogen, and
The metal halide lamp is characterized in that the amount M (mg / cc) of iron enclosed in the enclosure has a relationship of 0.001 <M <0.15 with respect to the volume of the discharge space.   2. The metal halide lamp according to claim 1, wherein the hermetic container is disposed in a water-cooled tube unit that cools by flowing a cooling liquid between an inner tube and an outer tube of a cooling tube including an inner tube and an outer tube.   A metal halide lamp characterized in that a protrusion is integrally formed on the outer periphery of the hermetic container regardless of whether there is a tube trace for introducing the inclusion.   2. The metal halide lamp according to claim 1, wherein the protrusion is formed higher than the tube mark when the tube mark is formed.   2. The metal halide lamp according to claim 1, wherein a plurality of the protrusions are provided in the lamp longitudinal direction.

Images