JPH07245081A - Ultraviolet ray setting lamp - Google Patents

Abstract

PURPOSE:To provide a UV-ray setting lamp of a long life in which life characteristics in the case of vertical lighting of the lamp can be improved, in which deterioration of an ultraviolet-ray output is small through the period of the lamp life, and which has no possibility of thermal deformation of a quartz light emission tube or leak of the light emission tube. CONSTITUTION:In a lamp for vertical lighting comprising main electrodes 3 sealed at both ends of a light emission tube 1, and light emitting metal enclosed inside, an insulation sleeve 7 comprising quartz is engaged at least around an electrode core rod 3a sealed on the lower side of the light emission tube 1 from an end of a sealed part 6a to an end surface of an electrode coil 3b of the core rod 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet curing lamp used in an ultraviolet curing device for curing a coating material for optical fibers and the like, and to improvement of life characteristics when the lamp is vertically lit.

[0002]

2. Description of the Related Art Optical fibers used for optical communication and the like are provided in order to prevent deterioration of strength due to scratches and dust on the surface thereof.
The drawn fiber is immediately coated with a UV-curable silicone, epoxy, urethane resin or the like to a thickness of several μm. FIG. 5 shows a schematic diagram of an optical fiber drawing process. The wire drawing device is provided with a heating furnace around the preformed base material, and a wire diameter measuring device from the lower end of the base material in the vertical direction, a primary coating portion including an ultraviolet curable resin coating device and an ultraviolet curing device, The fibers are sequentially guided to the capstan and the winding drum. Usually, the drawing speed is several tens to several hundreds m / min, and in order to realize such a speed, one or two or more ultraviolet lamps of about 10 KW are arranged side by side in the ultraviolet curing device. Also, FIG.
As is apparent from the above, the tube axis of the ultraviolet lamp installed in the ultraviolet curing device is lit and used in a vertical posture parallel to the drawing direction of the optical fiber.

[0003]

As shown in FIG. 6, an ultraviolet lamp used in an ultraviolet curing device has a pair of electrodes 22, 2 made of a high melting point material on both ends of a quartz arc tube 21.
3, in which at least one of mercury, rare gas, and halides such as iron (Fe), nickel (Ni), lead (Pb), gallium (Ga), magnesium (Mg), and tin (Sn) is provided in the arc tube. The above is added, and both ends thereof are hermetically sealed with the molybdenum foil 24 having airtightness and conductivity. And 2 which is effective for curing UV curable resin
It emits light with a wavelength of 50 to 450 nm.

When such a lamp is lit in the apparatus in a posture in which the tube axis is vertical, the metal halides in the tube are easily affected by convection and gravity, and easily collect under the arc tube. Therefore, the partial pressure of halogen in the lighting atmosphere in the vicinity of the lower electrode becomes relatively high, the reaction between the tungsten electrode and the additive is promoted, and the electrode is consumed much, resulting in the electrode core rod 23a.
The tip and the tungsten coil 23b become brittle even if they are repeatedly melted and recrystallized during lighting, and finally they collapse to form an irregularly shaped lump (hereinafter referred to as a metal lump 25) on the wall surface (cup portion 21a) at the lower end of the arc tube. To fall.

Then, the metal mass 25 of the collapsed electrode material
Starts to deposit around the electrode core rod 23a which is the bottom of the cup portion 21a as shown in FIG. Further, when the lamp is turned on again in the state as shown in FIG. 7, at the time of start-up, discharge starts from the metal lump portion, metal vapor is generated from the arc spot of the metal lump having a small thermal capacity, diffuses, and diffuses into the arc tube. It adheres to the wall, the ultraviolet transmittance of the quartz glass decreases, and the ultraviolet light output necessary for curing the resin cannot be obtained. On the other hand, the metal lumps heated by the discharge accelerate the temperature rise of the adhered quartz glass, causing crystallization and thermal deformation, and after lighting for several hundred hours, the cup part is thermally damaged, causing a leak and making the lamp defective. There is a problem that becomes.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and aims to improve the lamp life characteristics when the ultraviolet curing lamp used in the ultraviolet curing device is lit vertically, and to improve the life period. Therefore, it is an object of the present invention to provide a long-life UV curing lamp in which the decrease in the UV output is small, and the quartz tube is not thermally deformed or the arc tube is leaked.

In order to achieve the above object, the present invention is an ultraviolet curing apparatus for lighting a lamp in which a pair of electrodes are sealed at both ends of an arc tube and a luminescent metal is sealed inside so that the tube axis is lit in a vertical posture. In the above, an insulator is provided on the outer circumference of the core rod from the end of the sealing portion of the electrode core rod sealed at least on the lower side of the arc tube to the end face of the electrode coil. or,
An insulating sleeve made of quartz or alumina ceramic is fitted around the outer periphery of the core rod from the end of the sealing portion of the electrode core rod of the arc tube to the end face of the electrode coil. Furthermore, an insulating coating made of SiO ₂ or Al ₂ O ₃ is formed on the outer circumference of the core rod from the end of the sealing portion of the electrode core rod of the arc tube to the end face of the electrode coil.

[0008]

With the above structure, at the time of vertical lighting, an electrical insulator is interposed around the outer periphery of the electrode core rod, and a metal block melted and dropped from the tip of the electrode or the like does not electrically conduct to the electrode. Discharge can be prevented. The insulator may have a relatively simple structure such as fitting an insulating sleeve.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of an ultraviolet curing metal halide lamp of the present invention. A pair of electrodes 2 and 3 made of a refractory metal are hermetically sealed at both ends of a quartz arc tube 1 through a molybdenum foil 4, and Fe, S together with mercury and a rare gas are sealed inside.
It is a metal halide lamp in which one or more metal halides such as n, Co, Ni, Mg, Pb, and Ga that can provide effective light emission in the ultraviolet region are enclosed. Reference numeral 5 in the drawing denotes a terminal fitted in the sealing portion 6.

FIG. 2 is a sectional view of an essential part near the lower electrode of the lamp. The electrode 3 is sealed to the lower end sealing portion 5a of the arc tube 1 via the molybdenum foil 4a. Further, the tungsten coil 3 is wound around the tip of the electrode core rod 3a made of tungsten, and the electron emissive substance is held in the gap of the coil. An insulating sleeve 7 made of quartz is fitted to the outer circumference of the core rod from the end face of the lower end of the coil to the lower end cup portion of the arc tube where the electrode core rod is sealed.

Next, specific examples of the present invention will be described. The lamp has a total length of 630 mm, an outer diameter of 30 mm, and a distance between electrodes of 500 mm, and is filled with argon gas of 10 torr and mercury and halides of Fe and Sn in a quartz arc tube with a tube input of 12 kW and a load of 240 W / cm. It is designed. The electrode has an electrode core rod diameter of 2 mm and a total length of 20 mm, the coil wire diameter is 0.7 mm, and the total length of the coil is 6.5 mm.
In addition, the core rod projects about 1.5 mm from the tip of the coil.
A quartz sleeve having a thickness of about 3 mm and a thickness of 0.5 mm is fitted from the sealing surface of the core rod of the lower electrode of the arc tube to the lower end surface of the coil.

When the lamp is lit in a posture in which the tube axis is vertical, the metal halides are affected by convection and gravity and gather under the arc tube, and the partial pressure of halogen vapor near the lower electrode increases. . The halogen promotes the chemical reaction between the additive and the electrode like a catalyst, and the end of the electrode core and the coil melt and recrystallize by turning on and off, and become brittle, collapsing and irregular shape in the cup part. It becomes a lump of metal and falls. However, since the falling metal lump has an insulating sleeve made of quartz, it is electrically insulated from the electrode, so that the discharge from the metal lump does not occur. Therefore, the metal vapor is not generated from the metal block and the metal block is not overheated, so that the quartz is not thermally deformed.

When 20 such lamps were manufactured as a prototype and a life test was conducted, the characteristics shown in FIGS. 3 and 4 were obtained. As is clear from the figure, the relative UV output after 2000 hours of lighting is 60% in the conventional product,
The product of the present invention can maintain the relative ultraviolet light output at 80%. In addition, the remaining rate of the lamp after lighting for 2000 hours is
The product of the present invention was 80%, whereas the product of the present invention was 100%.

Although a 240 W / cm metal halide lamp has been described in the above embodiment, the same phenomenon as that of the present invention occurs because the same phenomenon as in the conventional case occurs when the lamp is vertically lit even if the lamp has a different load or a different total length. There is.
Also, the insulation sleeve should have heat resistance and insulation,
Materials other than quartz such as alumina ceramics and sapphire glass may be used. Further, in order to maintain such insulation, SiO 2 is formed on a predetermined surface of the electrode core rod by a CVD method or the like.
It is also possible to impart insulating properties by forming a coating film of ₂ or Al ₂ O ₃ . The insulating sleeve according to the present invention may be provided not only at the lower end portion of the arc tube but also at both ends of the arc tube when it is difficult to visually recognize the appearance of the lamp and it is easy to make an installation error in manufacturing and use. In this case, since there is no difference in the shape and size of the electrodes, there is no problem in terms of characteristics.

[0015]

As is apparent from the above description, the ultraviolet curing lamp according to the present invention is lit vertically by fitting an insulating sleeve or forming an insulating coating on the outer periphery of at least one electrode core rod. With this, it is possible to suppress the discharge from the metal lumps deposited on the lower side of the arc tube and to improve the characteristics of the ultraviolet ray output. Therefore, it is possible to obtain an ultraviolet curing lamp with a long life and good ultraviolet ray output characteristics. There is.

[Brief description of drawings]

FIG. 1 is a side view of an ultraviolet curing lamp according to the present invention.

FIG. 2 is a sectional view of the same main part.

FIG. 3 is a characteristic diagram showing a change in relative ultraviolet ray output of a lamp according to the present invention and a conventional lamp over time.

FIG. 4 is a characteristic diagram showing changes in the lamp residual ratio of a lamp according to the present invention and a conventional lamp over time.

FIG. 5 is a schematic view showing an optical fiber drawing process.

FIG. 6 is a side view of a conventional UV curing lamp.

FIG. 7 is a cross-sectional view of essential parts near a lower electrode of a conventional lamp after lighting for several hundred hours.

[Explanation of symbols]

 1 arc tube 1a cup part 2,3 electrode 3a electrode core rod 3b electrode coil 4 molybdenum foil 5 terminals 6,6a sealing part 7 insulating sleeve

Claims (3)

[Claims] 1. An ultraviolet curing device in which a pair of electrodes are sealed at both ends of an arc tube and a luminescent metal is sealed inside the lamp to turn on the lamp with the tube axis in a vertical posture. An ultraviolet curing lamp comprising an insulator on the outer circumference of the core rod from the end of the sealing portion of the electrode core rod sealed to the lower side to the end face of the electrode coil. 2. The ultraviolet ray according to claim 1, wherein an insulating sleeve made of quartz or alumina ceramic is fitted on the outer periphery of the core rod from the end of the sealing portion of the electrode core rod of the arc tube to the end face of the electrode coil. Curing lamp. 3. The outer periphery of the core rod from the end of the sealing portion of the electrode core rod of the arc tube to the end face of the electrode coil is made of SiO ₂ or Al ₂ O.
The ultraviolet curing lamp according to claim 1, wherein an insulating coating made of ₃ or the like is formed.