JP5217021B2 - Metal halide lamp - Google Patents

Description

  The present invention relates to a metal halide lamp used for curing an ultraviolet curable coating, a photoreaction of a functional polymer film, or the like.

The conventional metal halide lamp is an ultraviolet irradiation lamp having high emission intensity around 365 nm by suppressing metal ultraviolet light having a wavelength shorter than 340 nm by sealing metal thallium or thallium halide together with iron and mercury in an airtight container. Are known. (For example, Patent Document 1)
Japanese Patent Laid-Open No. 03-250549

  The technique disclosed in Patent Document 1 requires management of the arc tube temperature of 600 to 850 ° C. in order to ensure stable lighting of the lamp. When the temperature is higher than 850 ° C., the enclosed iron is impregnated into the hermetic container to cause a phenomenon of blackening, leading to a decrease in ultraviolet radiation intensity and bending of the lamp. For this reason, in order to lower the temperature of the lamp, it is conceivable to use an indirect cooling method by a water cooling method. In order to increase the cooling efficiency in the cooling method, it is necessary to keep the distance between the lamp and the cooling unit to about several mm.

  However, in recent years, there is a demand for longer lamps as the system becomes larger. In the case of the water cooling system, it is conceivable that the lamp is bent due to an increase in the lamp temperature due to the increase in length, and the lamp is brought into contact with the water cooling unit. When contact between the lamp and the water-cooled cooling unit occurs, the mercury in the lamp collects at the contact portion, thereby reducing the vapor pressure, and accordingly, the lamp voltage decreases. As a result, there is a problem that the ultraviolet radiation intensity is lowered.

  The object of the present invention is to limit the amount of mercury enclosed in the lamp, thereby suppressing not only the decrease in the ultraviolet radiation intensity and the bending of the airtight container due to the secular change as described above, but also the lamp extinction and flickering are suppressed. The object is to provide a metal halide lamp suitable for water-cooled cooling.

In order to solve the above-described problems, a metal halide lamp according to the present invention includes an airtight container having a discharge space that is airtight and made of an ultraviolet light transmissive material, and an axially-facing airtight container in the airtight container. A pair of discharge electrodes arranged and an enclosure made of a metal and a halogen that emits an appropriate amount of ultraviolet light together with a sufficient amount of rare gas and mercury to maintain an arc discharge state in the discharge space And a metal halide lamp comprising a cooling unit that encloses the hermetic container and circulates a cooling liquid to cool the hermetic container, and a lamp input per unit length of the hermetic container is 50 to 120 W / cm, The potential gradient D (V / cm) at the time of stable lighting has a relationship of 5.0 <D <15.0.

  According to the present invention, by limiting the amount of mercury enclosed in the lamp, not only the decrease in ultraviolet radiation intensity and the bending of the hermetic container due to aging etc. are suppressed, but also the water cooling type by suppressing lamp extinction and flickering. It is possible to obtain a metal halide lamp suitable for cooling.

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

FIG. 1 shows a basic structural diagram for explaining one embodiment of a thalhalide lamp of the present invention.
That is, for example, tungsten electrodes 121 and 122 are disposed inside the hermetic container 11 made of quartz glass having ultraviolet transparency and forming the discharge space 10 in the longitudinal direction. The hermetic container 11 is composed of a single tube having an outer diameter φ of 27.5 mm, a wall thickness m of 1.5 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 any material that has a thermal expansion coefficient close to that of quartz glass forming the hermetic container 11, but molybdenum is used as a material suitable for this condition. For example, the lead wires 161 and 162 for power feeding electrically connected inside the ceramic sockets 151 and 152 are insulated and sealed to the outer leads connected at one end to the molybdenum foils 141 and 142, respectively. Connected to the power circuit.

  In the airtight container 11, a sufficient amount of argon gas, which is a rare gas for maintaining arc discharge, is 1.3 kPa, and mercury, a metal for emitting ultraviolet light, iron, tin, indium, bismuth, At least one of thallium and manganese and a halogen are enclosed.

  Here, consider a case where the lamp voltage is 2300 V, the lamp current is 10.4 A, and the lamp is stably lit. Here, if the tube diameter is 27.2 mm or less, the distance between the arc and the arc tube becomes short, and blackening, devitrification, and bending of the lamp are caused by the rise of the arc tube temperature. On the other hand, when the tube diameter is 28.8 mm or more, the distance between the water-cooled tube and the arc tube is reduced, and the illuminance is reduced with a decrease in VL, so the tube diameter is in the range of 27.2 to 28.8 mm. Is described.

  When the potential gradient D (V / cm) is 4.9 or less and the mercury amount per 1 cc volume in the discharge space 10 is 0.39 mg, the temperature of the upper part of the hermetic vessel 11 rises to 850 ° C. As a result of the impregnated iron impregnated in the hermetic container 11 made of quartz glass, blackening, devitrification, and bending of the lamp occur.

  Further, when the potential gradient D (V / cm) is 15.1 or more and the amount of mercury per 1 cc volume in the discharge space 10 is 1.21 mg, flickering or extinction occurs, and stable lighting cannot be performed.

  Therefore, when the potential gradient D (V / cm) during stable lighting of the lamp is 11.5 and the amount of mercury M per 1 cc volume in the discharge space 10 is 0.9 mg, blackening, devitrification, It turns out that the bending of the lamp can be suppressed.

  Furthermore, even if the lamp is turned on with a potential gradient D (V / cm) of D <15.0 and an amount of mercury M per cc of the arc tube volume of M <1.2 mg, flicker and extinction due to a decrease in current value are suppressed. I understood.

  FIG. 4 shows the relationship between the potential gradient (V / cm) and the mercury amount (mg / cc). As can be seen from FIG. 4, the potential gradient (V / cm) and the mercury amount (mg / cc) are proportionally related. As a result of the experiment, blackening, devitrification, lamp, in a tube diameter of 27.2 to 28.8 mm, a potential gradient D of 5 to 15 V / cm, and a mercury amount M of 0.4 to 1.2 mg / cc. It was found that it was possible to suppress the bending of the.

FIG. 3 is an explanatory diagram for explaining a temperature change in the upper portion of the hermetic container 11 when the temperature gradient of the hermetic container 11 is set to a potential gradient D and a mercury amount M that can be set to less than 850 ° C.
3, when the lamp input is 120 W / cm, 100 mm from the position of the electrode 121 shown in FIG. 2 when the mercury amount is 0.34 mg / cc and when the mercury amount is 0.90 mg / cc. The result of having measured about the temperature change of the airtight container 11 upper part for every 10 mm in the distance to is shown.

  As apparent from FIG. 3, when the mercury amount is 0.34 mg / cc, the temperature exceeds 850 ° C. even at a position 100 mm away from the position of the electrode. On the other hand, when the mercury amount was 0.90 mg / cc, the temperature was about 820 ° C. even in the vicinity of the electrode where the temperature was highest in the vicinity of the electrode portion.

  From this result, the potential gradient (V / cm) and the mercury amount (mg) when the lamp input per unit length of the hermetic container is 27.2 to 28.8 mm in tube diameter and 50 to 120 W / cm input power. / Cc), if the potential gradient D is 5 to 15 V / cm and the mercury amount M is 0.4 to 1.2 mg / cc, the temperature of the upper part of the hermetic container 11 can be suppressed to 850 ° C. or less. As a result, blackening, devitrification, and bending of the lamp can be suppressed.

  FIGS. 5 and 6 are diagrams for explaining an embodiment in which the metal halide lamp of the present invention is used in an ultraviolet irradiation apparatus equipped with a water-cooling type cooling mechanism. FIG. 5 is a system configuration diagram, and FIG. It is II 'line sectional drawing of.

  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 41 a and 41 b attached to the sockets 151 and 152 of the metal halide lamp 100.

  The water cooling unit 200 is made 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. 6, the coolant 24 has a low temperature from the connecting pipe 23a, cools the metal halide lamp 100 from the connecting pipe 23b, and discharges the warmed water. The warmed water is cooled and input again from the connection pipe 23a.

A metal oxide film containing a metal oxide is deposited on the outer surface of the outer tube 22. The metal _{oxide, T i O 2, C e} O 2, Z n O 2, S n O 2, composed of at least one kind of Z r _{O 2.}

  The metal oxide film is component-adjusted so as to absorb a wavelength component of 300 nm or less of the light emitted from the metal halide lamp 100.

  When 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 rays having a wavelength range of 300 to 430 nm effective for curing the resin are transmitted through the water-cooling unit 200 and irradiated to an irradiated 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.

  When the potential gradient D (V / cm) is D> 5.0 and the mercury amount M per 1 cc of the arc tube volume is M> 0.4 mg, the temperature rise in the upper portion of the hermetic vessel 11 due to arc bending is reduced. Can be As a result, contact between the metal halide lamp 100 and the inner tube 21 of the water cooling unit 200 can be prevented, and blackening and devitrification can be suppressed. Further, the suppression of the temperature rise of the metal halide lamp 100 also contributes to the suppression of flickering and extinction.

1 is a basic structure diagram for explaining an embodiment of the present invention. FIG. 2 is an enlarged structural view of a part of FIG. 1. Explanatory drawing for demonstrating the relationship between electric potential gradient (V / cm) and mercury amount (mg / cc). Explanatory drawing for demonstrating the effect of this invention. The system block diagram for demonstrating the example which used the metal halide lamp of this invention for the ultraviolet irradiation device. FIG. 6 is a sectional view taken along line I-I ′ of FIG. 5.

Explanation of symbols

100 Metal Haloid Lamp 10 Discharge Space 11 Airtight Container 121, 122 Electrode 200 Water Cooling Unit 21 Inner Tube 22 Outer Tube 23a, 23b Connection Tube 24 Coolant

Claims (2)

An airtight container having a discharge space having airtightness with an ultraviolet ray transmitting material; and
A pair of discharge electrodes disposed oppositely in the hermetic container in the axial direction of the hermetic container;
A sufficient amount of rare gas, mercury to maintain an arc discharge in the discharge space, and an enclosure made of metal and halogen that emits an appropriate amount of ultraviolet light; and
In a metal halide lamp comprising a cooling unit that encloses the airtight container and circulates a cooling liquid to cool the airtight container ,
When the tube diameter of the hermetic container is 28.0 ± 0.8 mm and the lamp input power per unit length is 50 to 120 W / cm, the potential gradient D (V / cm) during stable lighting is 5.0 <D. <15.0, and the mercury amount M in the enclosed matter per 1 cc of the airtight container inner volume has a relationship of 0.4 mg <M <1.2 mg.   2. The metal halide lamp according to claim 1, wherein the metal that emits ultraviolet light is at least one of iron, tin, indium, bismuth, thallium, and manganese.

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