JP2023025358A - Metal halide lamp and UV irradiation device - Google Patents

Abstract

To provide a metal halide lamp and a UV irradiation device capable of prolonging the life of a lamp, even the life of log lamp.SOLUTION: A metal halide lamp according to an embodiment includes a cylindrical arc tube, and electrodes provided at both ends of the arc tube, respectively, and at least rare gas, mercury, iron, thallium iodide, mercury bromide, and mercury iodide are sealed inside the arc tube. The electrode has a filament provided inside the arc tube. The metal halide lamp satisfies the following formula when a distance L (m) between the filaments is 1 meter or more, and an amount of thallium enclosed per unit volume is T (μg/cc). T(μg/cc)≥4.177(μg/cc m)×L(m)-1.79(μg/cc).SELECTED DRAWING: Figure 5

Description

An embodiment of the present invention relates to a metal halide lamp and an ultraviolet irradiation device.

For example, an ultraviolet irradiation device equipped with a metal halide lamp is used for curing ultraviolet-curable adhesives and sealants, and for drying and curing ultraviolet-curable ink. A metal halide lamp provided in an ultraviolet irradiation device has an arc tube, and for example, a rare gas, a metal, a halogen, or the like is sealed inside the arc tube.

Metals enclosed inside the arc tube include, for example, mercury, iron, thallium, tin, magnesium, lead, zinc, and bismuth. In this case, the halogenated vapor of mercury and the halogenated vapor of iron are mainly the sources of ultraviolet radiation. Halogenated vapors other than mercury and iron, which can also be a source of ultraviolet radiation, are included primarily to suppress adhesion of iron to the inner wall of the arctube.

In this case, when the thallium is enclosed inside the arc tube, it is possible to suppress the adhesion of iron to the inner wall of the arc tube, and thus the reduction in the amount of enclosed iron, during lighting of the metal halide lamp. can. Furthermore, if thallium is sealed inside the arc tube, the illuminance of ultraviolet rays can be increased at the initial stage of lighting.

Here, in recent years, the size of the processed material is increasing. Therefore, a long metal halide lamp (having a long emission length) is desired. However, when the metal halide lamp becomes long, the amount of metal tends to be distributed in the axial direction of the arc tube. Further, when the metal halide lamp becomes long, it becomes difficult to uniformly cool the arc tube. Therefore, when the metal halide lamp is elongated, there is a problem that the life of the lamp is shortened.
Therefore, there has been a demand for the development of a technology that can extend the life of the metal halide lamp even if it is elongated.

JP 2020-107522 A

The problem to be solved by the present invention is to provide a metal halide lamp and an ultraviolet irradiating device that can have a long life even if they are long.

A metal halide lamp according to an embodiment includes a cylindrical arc tube; and electrodes provided at both ends of the arc tube. At least rare gas, mercury, iron, thallium iodide, mercury bromide, and mercury iodide are sealed inside the arc tube. The electrode has a filament provided inside the arc tube. The metal halide lamp satisfies the following formula, where the distance L (m) between the filaments is 1 meter or more and the amount of thallium enclosed per unit volume is T (μg/cc).
T (μg/cc)≧4.177 (μg/cc・m)×L (m)−1.79 (μg/cc)

According to the embodiments of the present invention, it is possible to provide a metal halide lamp and an ultraviolet irradiating device that can have a long life even if they are long.

1 is a schematic perspective view for illustrating an ultraviolet irradiation device according to an embodiment; FIG. 1 is a schematic cross-sectional view for illustrating a metal halide lamp; FIG. 4 is a table for illustrating the relationship between the emission length, the amount of thallium enclosed per unit volume, and the life of a metal halide lamp. FIG. 4 is a schematic diagram for exemplifying the measurement positions of the temperature of the arc tube; 4 is a graph showing the relationship between the emission length and the amount of thallium enclosed per unit volume in acceptable products.

Hereinafter, embodiments will be illustrated with reference to the drawings. In addition, in each drawing, the same reference numerals are given to the same constituent elements, and detailed description thereof will be omitted as appropriate.
FIG. 1 is a schematic perspective view for illustrating an ultraviolet irradiation device 1 according to this embodiment.
As shown in FIG. 1, the ultraviolet irradiation device 1 includes, for example, a housing 2, a mounting section 3, a cooling section 4, a reflector 5, a metal halide lamp 6, a power supply 7, and a controller 8.

A metal halide lamp 6 can be attached to the housing 2 . The housing 2 can be, for example, a chamber. In this case, the housing 2 can have an airtight structure to the extent that particles do not enter. Further, depending on the application of the ultraviolet irradiation device 1, the housing 2 without an airtight structure can be used. For example, the housing 2 may have a frame structure using elongated members.

A pair of holders 21 can be provided inside the housing 2 . A pair of holders 21 can be arranged side by side in the direction in which the metal halide lamp 6 extends. A pair of holders 21 can be attached to the reflector 5 or the housing 2 . Each of the pair of holders 21 holds an end portion (base 65) of the metal halide lamp 6. As shown in FIG.

A workpiece 100 to be irradiated with ultraviolet rays can be placed on the placing section 3 . A chuck or the like for holding the workpiece 100 can also be provided on the mounting section 3 . Moreover, the placement unit 3 may move the processing object 100 in the horizontal direction. For example, the placement section 3 may be an XY table, a conveyor, or the like.

The object to be treated 100 is not particularly limited as long as it requires ultraviolet irradiation. For example, the object to be treated 100 may have an ultraviolet curable adhesive, sealant, ink, paint, or the like adhered thereto. For example, the processed object 100 may have an alignment film such as a liquid crystal panel or a viewing angle compensation film.

The cooling unit 4 is connected to the exhaust port 51 of the reflector 5 via a duct 41 or the like, for example. When the air inside the concave portion 52 of the reflector 5 is exhausted by the cooling portion 4 , the air flows into the inside of the reflector 5 through the opening of the concave portion 52 of the reflector 5 . Therefore, for example, the metal halide lamp 6 can be cooled, and the gas generated in the workpiece 100 can be discharged. The cooling unit 4 is, for example, a sirocco fan or a blower.

Although the air-cooled cooling unit 4 is illustrated, a liquid-cooled cooling unit may be used. For example, the reflector 5 may be provided with a flow path through which the coolant flows, or a block having a flow path through which the coolant may flow may be provided in the vicinity of the arc tube 61 of the metal halide lamp 6 . The coolant can be, for example, water.

The reflector 5 is attached to the housing 2, for example. The reflector 5 may be attached to a member such as a bracket provided on the housing 2 or the like. Moreover, the reflector 5 can also be provided movably. In this case, by changing the distance between the reflector 5 and the metal halide lamp 6, it is possible to change the width of the irradiation region and the peak value of the intensity of the ultraviolet rays. Therefore, it is possible to change the width of the irradiation region and the peak value of the intensity of the ultraviolet rays according to the processing conditions.

A concave portion 52 is provided in the reflector 5 . The concave portion 52 opens to the lower surface 53 of the reflector 5 (the surface of the reflector 5 on the mounting portion 3 side). Although the block-shaped reflector 5 is exemplified, the reflector may be formed by bending a plate-shaped member.

A metal halide lamp 6 is provided in the internal space of the recess 52 . The inner surface of the recess 52 is a reflective surface. A film containing a highly reflective metal can be provided on the inner surface of the recess 52 . Also, the inner surface of the concave portion 52 can be polished so as to have a glossy surface. When viewed from the direction in which the metal halide lamp 6 extends, the contour of the recess 52 can include curved lines, straight lines, or both curved lines and straight lines. A curve can be, for example, a portion of a circle, a portion of an ellipse, a parabola, or the like.

Part of the ultraviolet rays emitted from the metal halide lamp 6 is directly applied to the workpiece 100 . Further, the ultraviolet rays irradiated from the metal halide lamp 6 and incident on the inner surface of the concave portion 52 are reflected toward the object 100 to be processed. By providing the reflector 5, the utilization efficiency of ultraviolet rays can be improved.

An exhaust port 51 can be provided on an upper surface 54 of the reflector 5 (the surface of the reflector 5 opposite to the mounting portion 3 side). The exhaust port 51 communicates with the internal space of the recess 52 . For example, the exhaust port 51 penetrates between the upper surface 54 and the inner surface of the recess 52 . A plurality of exhaust ports 51 can be provided. A plurality of exhaust ports 51 can be arranged side by side in the direction in which the metal halide lamp 6 extends. The number, arrangement, cross-sectional dimensions, and the like of the exhaust ports 51 can be appropriately determined according to the length of the metal halide lamp 6, the temperature, and the like. The number, arrangement, cross-sectional dimensions, and the like of the exhaust ports 51 can be appropriately determined through experiments and simulations.
Also, one exhaust port (for example, a slit-shaped exhaust port) extending in the direction in which the metal halide lamp 6 extends may be provided. That is, at least one exhaust port 51 may be provided.

A band-pass filter 55 can also be provided between the opening of the concave portion 52 of the reflector 5 and the mounting portion 3 . The band-pass filter 55 can have, for example, a plate shape, absorb visible light, and transmit ultraviolet light. In this case, the bandpass filter 55 may transmit ultraviolet rays of a specific wavelength.

Although FIG. 1 illustrates the case where one metal halide lamp 6 is provided, a plurality of metal halide lamps 6 can be provided. When a plurality of metal halide lamps 6 are provided, the plurality of metal halide lamps 6 can be arranged side by side in a direction substantially orthogonal to the extending direction of the metal halide lamps 6 . Also, a plurality of sets of reflectors 5 and metal halide lamps 6 can be provided.

The metal halide lamp 6 can be, for example, a high intensity discharge lamp (HID) capable of emitting light containing ultraviolet rays.
FIG. 2 is a schematic cross-sectional view for illustrating the metal halide lamp 6. As shown in FIG.
As shown in FIG. 2, the metal halide lamp 6 has, for example, an arc tube 61, an electrode 62, a conductive foil 63, an outer lead 64, a base 65, and a lead wire 66.

The arc tube 61 is provided inside the recess 52 of the reflector 5 . The arc tube 61 has a cylindrical shape and is made of a heat-resistant and translucent material. The material of the arc tube 61 is quartz, glass, or the like, for example.

A discharge medium is sealed inside the arc tube 61 . Discharge media include, for example, noble gases, metals, and halogens such as iodine and bromine.
Rare gases are, for example, xenon, argon, or mixed gases thereof. The pressure of the gas inside the arc tube 61 at 25° C. (the pressure of the rare gas enclosed) can be, for example, 133 Pa or more. The gas pressure at 25° C. inside the arc tube 61 can be obtained from the standard state of the gas (SATP (Standard Ambient Temperature and Pressure): temperature 25° C., pressure 1 bar).

Metals are, for example, mercury, iron, thallium, tin, indium, magnesium, manganese, bismuth, and the like.
For example, halogenated vapors of mercury and halogenated vapors of iron are major sources of ultraviolet radiation. Further, for example, if thallium, magnesium, bismuth, etc., are further included, reduction of iron can be suppressed by these metal halide vapors. For example, when halogenated vapor of thallium is contained inside the arc tube 61, iron is suppressed from adhering to the inner wall of the arc tube 61, thereby suppressing reduction of iron.
In other words, the arc tube 61 is filled with at least rare gas, mercury, iron, thallium iodide, mercury bromide, and mercury iodide.

A sealing portion 61 a is provided at each of both ends of the light emitting tube 61 . By providing the sealing portions 61a at both ends of the arc tube 61, the inside of the arc tube 61 can be hermetically sealed. For example, the pair of sealing portions 61a can be formed using a pinch seal method or a shrink seal method.

Electrodes 62 are provided at both ends of arc tube 61 . For example, electrode 62 has filament 62a and inner lead 62b. The filament 62a and the inner lead 62b can be integrally formed using a linear member. The linear member includes, for example, tungsten, rhenium-tungsten alloy, and the like.

The filament 62 a is provided inside the arc tube 61 . The distance between the filaments 62a is the emission length L. As shown in FIG. For example, the filament 62a is a spirally wound linear member.
One end of the inner lead 62 b is connected to the filament 62 a inside the arc tube 61 . The other end of the inner lead 62b is connected to the conductive foil 63 inside the sealing portion 61a. The inner lead 62b and the conductive foil 63 can be connected by, for example, laser welding or resistance welding.

One conductive foil 63 can be provided for one sealing portion 61a. The conductive foil 63 is provided inside the sealing portion 61a. The planar shape of the conductive foil 63 is, for example, a quadrangle. The conductive foil 63 is made of molybdenum foil, for example.

At least one outer lead 64 is provided for one conductive foil 63 . The outer lead 64 has a linear shape. One end of the outer lead 64 is connected to the conductive foil 63 inside the sealing portion 61a. The outer lead 64 and the conductive foil 63 can be connected by, for example, laser welding or resistance welding. The other end side of the outer lead 64 is exposed to the outside of the sealing portion 61a. The outer leads 64 are made of, for example, molybdenum wire.

One base 65 can be provided for one sealing portion 61a. The base 65 has a tubular shape, for example, and covers the portion of the outer lead 64 exposed from the sealing portion 61a. The base 65 is made of, for example, an insulating material such as ceramics. As shown in FIG. 1, arc tube 61 is attached to holder 21 via base 65 .

One lead wire 66 can be provided for one base 65 . One end of the lead wire 66 is electrically connected to the outer lead 64 inside the base 65 . The other end of lead wire 66 is electrically connected to power supply 7 . A crimp terminal, a connector, or the like can be provided at the other end of the lead wire 66 .

The power supply 7 is electrically connected to the electrodes 62 via lead wires 66 , outer leads 64 and conductive foils 63 . A power supply 7 supplies predetermined power to the electrodes 62 . When power is supplied to the electrodes 62, discharge occurs between the filaments 62a. The electrons generated by the discharge collide with enclosed mercury atoms and iron atoms inside the arc tube 61 . Ultraviolet radiation is produced when electrons collide with mercury and iron atoms. The generated ultraviolet rays are irradiated to the outside of the arc tube 61 . The metal halide lamp 6 is an example of a long arc type high intensity ultraviolet lamp.

The controller 8 controls the operation of each element provided in the ultraviolet irradiation device 1 . The controller 8 has, for example, an arithmetic unit such as a CPU (Central Processing Unit), and a storage unit such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive). The controller 8 can be, for example, a computer or the like.

The storage unit can store, for example, a control program for controlling the operation of each element provided in the ultraviolet irradiation device 1 .

The controller 8 can also be connected to a host computer or the like installed in a factory or the like. An input device for inputting data by a worker or the like and a display device for displaying the operating state of the ultraviolet irradiation device 1 can be appropriately connected to the controller 8 .

In addition, necessary elements can be appropriately added to the ultraviolet irradiation device 1 according to the contents of the process. For example, when the ultraviolet irradiation device 1 performs alignment treatment on an alignment film such as a liquid crystal panel or a viewing angle compensation film by a photo-alignment method, the ultraviolet irradiation device 1 can be provided with a polarizer. A polarizer can be provided, for example, between the metal halide lamp 6 and the mounting section 3 . The polarizer can be, for example, a wire grid polarizer. If a polarizer is provided, the alignment film of the workpiece 100 can be irradiated with polarized light including ultraviolet rays. Therefore, the alignment film of the processed object 100 can be subjected to the alignment treatment by the photo-alignment method.

Here, the service life of the metal halide lamp 6 will be explained. As mentioned above, one of the main sources of UV radiation is the iron contained in the discharge medium. Iron adheres to the inner wall of the arc tube 61 as the metal halide lamp 6 is lit. When iron adheres to the inner wall of arc tube 61, the amount of iron that contributes to the radiation of ultraviolet rays is reduced, so the illuminance of ultraviolet rays is reduced. Therefore, replacement of the metal halide lamp 6 is required.

In this case, as described above, if the discharge medium further contains thallium, magnesium, bismuth, or the like, it is possible to suppress adhesion of iron to the inner wall of arc tube 61 and, in turn, reduce the amount of iron. Further, when the discharge medium contains thallium, the illuminance of ultraviolet rays can be increased at the initial stage of lighting of the metal halide lamp 6 . If the illuminance of ultraviolet rays can be increased at the initial stage of lighting of the metal halide lamp 6, it is suitable for, for example, curing of ultraviolet curing adhesives and sealants, and drying and curing of ultraviolet curing inks.

Therefore, if at least mercury, iron, and thallium are used as the metals contained in the discharge medium, the life of the metal halide lamp 6 can be lengthened, and the illuminance of the ultraviolet rays can be increased at the initial stage of lighting the metal halide lamp 6. .

Here, in recent years, as the object 100 to be processed has become larger, a long metal halide lamp 6 (having a long light emitting length L) is required. For example, there are cases where a metal halide lamp 6 having a light emission length L of 1 meter or more is required.

As the metal halide lamp 6 becomes longer, the distribution of the amount of metal tends to occur in the axial direction of the arc tube 61 . When the amount of metal is distributed, the temperature of the arc tube 61 is also distributed in the axial direction of the arc tube 61 . In this case, the service life of the metal halide lamp 6 is shortened if the temperature of the arc tube 61 becomes too high.

As described above, since the cooling unit 4 is provided in the ultraviolet irradiation device 1, it is possible to suppress the temperature of the light emitting tube 61 from rising partially. However, when the metal halide lamp 6 becomes long, it becomes difficult to uniformly cool the arc tube 61 .
Therefore, if the metal halide lamp 6 becomes long, the life of the metal halide lamp 6 may be shortened even if thallium is included in the discharge medium to suppress the decrease in the amount of iron. In this case, if the metal halide lamp 6 has a light emission length L of 1 meter or more, the life of the metal halide lamp 6 tends to be further shortened.

As a result of investigation by the present inventors, it has been found that if the amount of thallium enclosed per unit volume is adjusted in accordance with the light emission length L, the life of the long metal halide lamp 6 can be lengthened.
The relationship between the emission length L, the amount of thallium enclosed per unit volume, and the life of the metal halide lamp 6 will be described below.

FIG. 3 is a table illustrating the relationship between the light emission length L, the amount T of thallium enclosed per unit volume, and the life of the metal halide lamp 6. As shown in FIG.
FIG. 4 is a schematic diagram for exemplifying the measurement positions of the temperature of the arc tube 61. As shown in FIG.
The discharge medium enclosed in arc tube 61 contains at least rare gas, mercury, iron, thallium iodide, mercury bromide, and mercury iodide. Xenon was used as the rare gas, and the sealing pressure was about 50Toor (6.67kPa).

The lifetime of the metal halide lamp 6 was evaluated by fabricating samples in which the light emission length L and the amount of thallium enclosed per unit volume T were changed and performing a lighting test.
The metal halide lamp 6 was lit so that the power density was "W (kW)/L (m)>12 (kW/m)". Note that W is the power supplied to the electrode 62 . For example, in the lighting test shown in FIG. 3, the power density (W (kW)/L (m)) was set to 16 kW/m (160 W/cm). When the metal halide lamp 6 is lit with such a high power density, the temperature of the arc tube 61 rises. In this case, increasing the amount of exhaust gas from the cooling unit 4 can prevent the temperature of the arc tube 61 from rising.

However, in the case of a long metal halide lamp 6 with a high power density, it is difficult to keep the temperature distribution within 50° C. even if the exhaust amount of the cooling section 4 is increased. Therefore, in the lighting test, at the five measurement points shown in FIG. 4, the maximum temperature was 850.degree. It is more preferable to control the cooling unit 4 so that the surface temperature of the arc tube 61 varies within 80° C. in the axial direction of the arc tube 61 .

The life of the metal halide lamp 6 was determined by the illuminance maintenance rate when the lighting time reached 3000 hours. The illuminance maintenance rate is "measured illuminance/illuminance at the beginning of lighting". The illuminance was the illuminance of ultraviolet light with a wavelength of 365 nm. A pass condition is an illuminance maintenance rate of 70% or more. "O" in FIG. 3 indicates pass, and "x" indicates failure.
As can be seen from FIG. 3, if the amount T of thallium enclosed per unit volume is adjusted according to the light emission length L, even the long metal halide lamp 6 can have a longer life.

FIG. 5 is a graph showing the relationship between the emission length L and the amount of thallium enclosed per unit volume T in acceptable products.
As can be seen from FIG. 5, even if the emission length L is 1 meter or more, the amount T of thallium enclosed per unit volume is "T (μg/cc)≧4.177 (μg/cc·m)×L ( m)-1.79 (μg/cc), the metal halide lamp 6 can be lit for 3000 hours or longer. That is, if the amount T of thallium enclosed per unit volume is "T (μg/cc) ≥ 4.177 (μg/cc m) x L (m) - 1.79 (μg/cc)," A metal halide lamp 6 having a long service life can be obtained.

Although some embodiments of the present invention have been illustrated above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, etc. can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof. Moreover, each of the above-described embodiments can be implemented in combination with each other.

1 ultraviolet irradiation device, 4 cooling unit, 6 metal halide lamp, 61 arc tube, 62 electrode, 62a filament, L emission length, T amount of thallium enclosed per unit volume

Claims (4)

A cylindrical arc tube;
electrodes respectively provided at both ends of the arc tube;
and
At least rare gas, mercury, iron, thallium iodide, mercury bromide, and mercury iodide are sealed inside the arc tube,
The electrode has a filament provided inside the arc tube,
The distance L (m) between the filaments is set to 1 meter or more,
A metal halide lamp that satisfies the following formula, where T (μg/cc) is the amount of thallium enclosed per unit volume.
T (μg/cc)≧4.177 (μg/cc・m)×L (m)−1.79 (μg/cc) 2. A metal halide lamp according to claim 1, which satisfies the following equation, where W (kW) is the power supplied to said electrode.
W (kW)/L (m) > 12 (kW/m) An ultraviolet irradiation device comprising the metal halide lamp according to claim 1 or 2. a cooling unit for cooling the arc tube of the metal halide lamp;
further comprising
4. The ultraviolet irradiation device according to claim 3, wherein the surface temperature of said arc tube varies by 50[deg.] C. or more in the axial direction of said arc tube.

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