WO2003021173A1

WO2003021173A1 - Uv radiation device

Info

Publication number: WO2003021173A1
Application number: PCT/EP2002/009177
Authority: WO
Inventors: Wolfgang Kiefer
Original assignee: Dr. Hönle AG
Priority date: 2001-08-31
Filing date: 2002-08-16
Publication date: 2003-03-13
Also published as: TWI224342B; DE20114380U1

Abstract

The invention relates to a radiation device (10; 30) for exposing objects (26) to UV radiation. Said device comprises an oblong UV lamp (12) for emitting UV radiation, and a first oblong reflector (21) consisting of highly-reflective material, extending along the UV lamp (12), and partially surrounding the same. A first (24) and a second (25) of the first opposing longitudinal sides occlude the first oblong reflector (21) and define a through opening (22) for the UV radiation. The inventive device also comprises a second oblong reflector (23a; 23b) consisting of highly-reflective material, which is connected to the first longitudinal side (24) of the first oblong reflector (21), and reflects UV radiation from the UV lamp or from the first oblong reflector towards an outlet (14) which is connected to the second longitudinal side (25). The second oblong reflector (23a; 23b) is curved at least partially about an axis (A) which is parallel to the oblong UV lamp.

Description

"UV irradiator"

The present invention relates to a UV irradiation device for irradiating objects with ultraviolet radiation (UV radiation).

Such UV radiation devices for irradiating objects with UV radiation are manufactured and sold, for example, by the applicant in various configurations and are used, among other things, for drying and curing adhesives, paints, plastics, etc. Fields of application are, for example, the irradiation of compact discs, digital Video discs etc.

A known UV irradiation device of the type described is shown in FIG. 7, which represents a cross section through the generally elongated UV irradiation device 70. The known UV irradiation device 70 comprises an elongated reflector 71 consisting of two parts 71a, 71b with layers 70a, 70b made of highly reflective material, which extends along an elongated UV lamp 72 for emitting UV radiation. The elongated reflector 71 and the UV lamp 12 are located in a housing 73. The UV lamp 72 shown in cross section emits UV radiation on all sides, the UV radiation imitated upwards in the drawing plane of FIG. 7 by the two Reflector layers 70a and 70b is reflected down to a passage opening 75. The passage opening 75 is delimited by a first long side 76 of the reflector part 71b and a second long side 77 of the second reflector part 71a. An elongated holder 80 for a further reflector 78 is connected to the first longitudinal side 76 of the first reflector part 71b. The reflector 78 comprises a flat surface made of highly reflective material and is clamped in the reflector holder 80. The reflector 78 reflects UV radiation emitted directly by the UV lamp 72 and UV radiation reflected by the reflector layers 70a and 70b to an outlet opening 74 which adjoins the second longitudinal side 77 of the second reflector part 71a. The UV radiation falling through the outlet opening 74 is used to irradiate objects 79 which are placed in front of the outlet opening 74 or are moved along it. The dwell time of the objects 79 in front of the outlet opening 74 and the type of UV lamps 72 used here vary depending on the type of objects to be irradiated and on the purpose of the UV radiation. A problem with the irradiation of objects with UV radiation is the infrared (IR) radiation simultaneously generated by the UV lamps. The IR radiation also radiated onto the objects can lead to a strong heating of the objects and consequently to damage to the irradiated objects. Various measures are possible to solve this problem. For example, the irradiated objects 79 can be cooled with water cooling in order to remove the heat generated by the IR radiation and to ensure efficient drying or curing by the UV radiation. However, water cooling is associated with a very high outlay and cannot usually be integrated into the manufacturing process. A further possibility is the use of a reflector made of dichroic material for the reflector 78. Since practically all of the UV radiation emitted by the UV lamp 72 either falls directly onto the further reflector 78 or is reflected by the reflector layers 70a and 70b, this can pass through here the use of dichroic material the IR portion of UV radiation can be greatly reduced. Dichroic material can also be used for the reflector layers 70a and 70b. The disadvantage of using dichroic material is that the reflection losses reduce the UV radiation efficiency. The UV radiation efficiency is further reduced by the use of the additional reflector 78 as a result of the losses due to the longer beam path. Another problem is that although the reflector 78 can filter out a relatively high IR component from the UV radiation, the resulting heat is not particularly effective as a result of the material transitions between the reflector and air reflector holder. Furthermore, the design of the reflector 78 with a flat reflection surface has not proven to be advantageous with regard to the homogeneity and the strength of the UV radiation incident on the object 79.

The object of the present invention is therefore to provide an irradiation device for irradiating objects with UV radiation, which enables irradiation of the object in the simplest and most effective way possible, in particular with regard to the necessary power and the heating of the object. '

The above object is achieved by an irradiation device for irradiating objects with UV radiation according to spoke 1. The irradiation device according to the invention comprises an elongated UV lamp for emitting UV radiation, a first elongated reflector made of highly reflective material which extends along and partially encloses the UV lamp, a first and a second of the first longitudinal side opposite the first elongated side Complete the reflector and define a passage opening for the UV radiation, a second elongated reflector made of highly reflective material, which is located on the first long side of the first elongated reflector and reflects UV radiation coming from the UV lamp or from the first elongated reflector to an outlet opening which adjoins the second longitudinal side, the second elongated reflector at least partially around an axis parallel to the elongated UV lamp is curved.

The at least partially curved shape of the second reflector results in a significantly improved distribution of the UV radiation incident on an object to be irradiated.

Advantageously, the second elongate reflector has a substantially flat area towards the outlet opening. This larger or smaller flat area near the outlet opening, depending on the application, ensures that UV radiation coming from the irradiation device is actually reflected onto the object to be irradiated and not back into the irradiation device. This increases the radiation efficiency.

Alternatively, the second elongated reflector can be completely curved around one or more axes parallel to the elongated UV lamp. This configuration can be advantageous in special applications. Furthermore, a completely curved reflector may be easier and therefore cheaper to manufacture.

The second elongate reflector advantageously has regions with different radii of curvature. By using different radii of curvature, the homogeneity distribution and the efficiency of the UV radiation incident on an object to be irradiated can be tailored precisely to the requirements. Furthermore, this makes it possible to connect the second reflector to the first reflector continuously, that is to say without kinks or other obstacles interfering with the reflection of the UV radiation. It is particularly advantageous here if the second elongate reflector has a smaller radius of curvature in a first region adjoining the first longitudinal side of the first elongate reflector than in a second region adjoining the first region.

It is also advantageous if the second elongated reflector has no kinks. In other words, the surface of the second reflector can be continuously differentiated in cross section. This minimizes reflection losses.

The highly reflective material of the second elongated reflector is advantageously vapor-deposited directly onto a reflector element provided with cooling ribs. hereby efficient absorption and derivation of the IR portion of the UV radiation absorbed by the second reflector is made possible. The reflector element is advantageously an extruded aluminum profile. It is also advantageous if the highly reflective material of the second elongate reflector is a dichroic material. Such a material enables a particularly high absorption of the IR component of the incident UV radiation. This ensures that the UV radiation incident on the object to be irradiated has the lowest possible IR component and thus the heat development in the object to be irradiated is minimal.

Preferred exemplary embodiments of the present invention are explained in more detail in the following description with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic front view of an irradiation device according to the invention,

FIG. 2 shows a schematic sectional view of a first exemplary embodiment of an irradiation device according to the invention,

FIG. 3 shows a schematic sectional view of a second exemplary embodiment of an irradiation device according to the invention,

Figure 4 shows a more accurate representation of the second reflector in

FIG. 3 shows the exemplary embodiment shown,

Figure 5 is a more detailed representation of the first shown in Figure 4

Embodiment,

FIG. 6 shows a comparison diagram of the irradiance levels per cross-sectional area for the first and the second exemplary embodiment of the irradiation device according to the invention and the known irradiation device shown in FIG. 7, and

Figure 7 is a schematic sectional view of a known radiation device.

FIG. 1 shows a schematic front view of an irradiation device 10 according to the invention for irradiating objects with UV radiation. The irradiation device 10 comprises a housing 11 in which an elongated UV lamp is arranged for emitting UV radiation. The UV lamp is located in an upper part of the housing 11. Below the housing 11, the irradiation device 10 according to the invention comprises a reflector holder 13, which receives the UV radiation coming from the UV lamp 12 or from the reflectors surrounding this UV lamp 12 at the front to an outlet opening 14, that is to say reflected from the plane of the drawing.

FIG. 2 shows a cross section of the irradiation device 10 shown in FIG. 1. In the housing 11 there is a first elongated reflector 21 with an essentially elliptical shape in cross section. The UV lamp 12, that is to say its longitudinal axis A, lies essentially on the focal point of the ellipse formed by the reflector. The first elongated reflector 21 comprises two reflecting layers 20a and 20b, which partially enclose the UV lamp 12 and reflect the UV radiation emitted by the UV lamp 12 in the direction of a passage opening 22. The passage opening 22 is defined by a first longitudinal side 24 and a second longitudinal side 25 opposite the first longitudinal side 24, which terminate the first elongated reflector 21 on both sides. The two reflector layers 20a and 20b are each vapor-deposited onto an aluminum profile 21a or 21b or attached to the associated aluminum profile as a separate reflector layer. On the rear sides, the two aluminum profiles 21a and 21b have cooling fins through which the energy released in the form of heat when the UV radiation is reflected is removed by appropriate coolants, for example water or air. The essentially elliptical shape of the first elongated reflector 21 ensures a very homogeneous and efficient reflection of the UV radiation to the passage opening 22, that is to say downwards in the illustrated FIG. 2.

The reflector holder 13 already mentioned with reference to FIG. 1 is connected to the first longitudinal side 24 of the first reflector 21. The reflector holder 13 comprises a second reflector 23a, which reflects UV radiation coming through the passage opening 22 to an outlet opening 14 which adjoins the second longitudinal side 25 of the first reflector. In the exemplary embodiment shown in FIG. 2, the outlet opening 14 extends essentially perpendicular to the through opening 22, so that objects 26 located in front of the outlet opening 14 and which are irradiated with the UV radiation do not receive any direct UV radiation from the UV lamp 12. but essentially only UV radiation reflected by the first reflector 21 and the second reflector 23a. The object or objects 26 irradiated with UV radiation are either moved along the exit opening 14 or remain statically in one place for a specific irradiation time. The irradiation device 10 according to the invention can be used to irradiate objects 26 of any type and for any type of application. However, the irradiation device 10 according to the invention is specially designed for drying and curing UV-reactive paints, varnishes or adhesives. The UV lamp 12 can also be any type of UV lamp, such as gas discharge lamps of different pressure ranges. A medium-pressure gas discharge lamp as UV lamp 12 is advantageous for the preferred applications mentioned above. The discharge lamp can have different types of doping, for example a gallium doping, a mercury doping or the like. As an alternative, a metal halogenite emitter can also be used. The arc length, the selected power and the exposure time are each to be matched to the size of the object 26 to be irradiated and to the purpose of the irradiation.

To ensure good radiation efficiency when irradiating the object 26, the second elongated reflector 23a is at least partially curved about an axis parallel to the UV lamp 12, that is to say its longitudinal axis A. The curvature of the second reflector 23 a can be clearly seen in the cross section of FIG. 2. The second reflector 23a is essentially composed of two regions, namely a first region 27a, which directly adjoins and is curved on the first longitudinal side 24 of the first reflector, and a second region 28a, which adjoins the outlet opening 14 and one in has a substantially flat surface. This shape of the second reflector 23a achieves the radiation efficiency and an increase in the radiation dose of the UV radiation radiated onto the object 26.

The highly reflective material of the first reflector 20a, 20b and the second reflector 22a is advantageously high-purity aluminum. High-purity aluminum means, for example, a degree of purity of 99.99% aluminum, through which the UV radiation is reflected with practically no loss on the objects to be irradiated. However, the use of dichroic reflectors for the layers 20a and 20b of the first reflector 21 and for the second reflector 23a is particularly advantageous. The chroitic reflectors are particularly advantageous because they reduce the IR portion of the radiation by approximately 25% when reflecting the UV radiation. The heat generated by the absorbed IR component is removed by suitable coolants.

FIG. 3 shows the cross section of a second exemplary embodiment of an irradiation device 30 according to the invention. The irradiation device 30 differs only in the shape of the housing and the second reflector 23b from the irradiation device 10 shown in FIGS. 1 and 2, so that all of the above statements also apply to the second exemplary embodiment. In contrast to the radiation device 10, the radiation device 30 has a somewhat larger housing 31, in which the housing 11 is fastened via an inner housing 32, in which the first reflector 21 and the UV lamp 12 are arranged, as with reference to FIG. 2 was explained. Another difference is the shape of the second reflector 23b. The general division into a curved region 27b and a flat region 28b adjoining the outlet opening 14 is identical to the irradiation device 10. However, the flat region 28b is somewhat longer than the flat region 28a of the first exemplary embodiment, so that the entire surface of the second In the second exemplary embodiment, the reflector 23b extends to the outer edge of the outer housing 31 and thus the outlet opening 14 is again arranged essentially at right angles to the passage opening 22. In other words, the flat surface 28b is somewhat elongated in comparison to the flat surface 28a in order to take into account the larger housing. All other essential properties and functions of the radiation device 30 correspond to those of the radiation device 10.

FIG. 4 shows a schematic illustration of the second reflector 23a of the irradiation device 30 from FIG. 3. The curved area 27b of the second reflector 23b is divided into different areas with different radii of curvature. In a first region 40, which directly adjoins the first longitudinal side 24 of the first reflector, the second reflector 23b has a medium-sized radius, 90.78 cm in the example shown. In a central region 41, which adjoins the first region 40, the second reflector 23b has a large radius of 114.50 cm in the example shown. In a third area 42, which is located between the middle area 41 and the flat area 28b, the second reflector 23b has a small radius of 50.0 cm. The length of the flat area is 43.41 cm in the example shown. The shape of the second reflector 23b shown in FIG. 4 is an optimized shape with regard to the radiation efficiency and radiation dose of the UV radiation impinging on the object 26. Deviations from this special form for certain applications are possible. However, it has been shown that the configuration of the second reflector 23b with at least two regions of different curvature and a flat region towards the outlet opening 14 has particular advantages. It should also be emphasized that the second reflector 23a of the irradiation device 10 can also have regions 40, 41 and 42 which are curved very similarly or identically to the second 4. The reflector 23b of FIG. 4. Only the flat surface 28a of the second reflector 23a of the irradiation device 10 is somewhat shorter than the flat surface 28b of the second reflector 23b.

It should also be emphasized that in the transition between the flat region 28a or 28b and the curved regions 27a or 27b there is advantageously no kink in the surface of the second reflector 23a or 23b and that the line of the second reflector 23a or 23b cross-section is continuously differentiable, so to speak. This guarantees a maximum of the reflection yield.

Figure 5 shows a somewhat more detailed cross-section of the first embodiment of the irradiation device according to the invention shown in Figure 2 10. The second reflector 23 comprises an aluminum profile 50 with cooling fins 51 which project from the surface of the second ^• reflector 23a back to the reflector holder. 13 The cooling and the removal of the heat takes place via suitable coolants, such as air or water. The second reflector 23a is advantageously vapor-deposited directly onto the aluminum profile 50, as a result of which the efficiency of heat dissipation is significantly increased since the heat absorbed during the reflection of the UV radiation is transferred directly to the aluminum profile 50 and its cooling fins 51. The same principle is advantageously used for the first reflector 21, the layers 20a, 20b of which can also be evaporated onto the aluminum profiles 21a and 21b. This technology ensures efficient absorption of the IR component from the reflected UV radiation and reliable removal of the heat developed. As a result, the temperature introduced into the object when the object 26 is irradiated drops considerably, the reflection losses and the longer beam path of the UV radiation being more than compensated for by the special geometry of the second reflector 23a. The above statements also apply identically to the radiation device 30.

FIG. 6 shows a diagram of the power radiated per area in relation to the cross-sectional area of the object 26 to be irradiated for the known irradiation device 70 (curve I) shown in FIG. 7, the irradiation device 10 (curve II) and the irradiation device 30 (curve III). It can be seen that the special geometry of the second reflector 23a and 23b of the irradiation devices 10 and 30 according to the invention has an increase of approximately 80% in the tip and an increase of approximately 30% in relation to the total irradiated on the object 26 Allow dose.

Claims

Expectations

1. Irradiation device (10; 30) for irradiating objects (26) with UV radiation, with an elongated UV lamp (12) for emitting UV radiation, a first elongated reflector (21) made of highly reflective material which extends lengthways the UV lamp (12) extends and partially encloses it, a first (24) and a second (25) of the first opposite long side terminating the first elongated reflector (21) and defining a passage opening (22) for the UV radiation, a second elongated reflector (23a; 23b) made of highly reflective material, which adjoins the first longitudinal side (24) of the first elongated reflector (21) and UV radiation coming from the UV lamp or from the first elongated reflector to an outlet opening ( 14), which adjoins the second longitudinal side (25), the second elongated reflector (23a; 23b) being at least partially curved around an axis (A) parallel to the elongated UV lamp.

2. Irradiation device (10; 30) according to claim 1, characterized in that the second elongated reflector (23a; 23b) towards the outlet opening (14) has a substantially flat region (28a; 28b).

3. Irradiation device according to claim 1, characterized in that the second elongated reflector is completely curved about one or more axes parallel to the elongated UV lamp.

4. Irradiation device (10; 30) according to claim 1, 2 or 3, characterized in that the second elongated reflector (23a; 23b) has areas with different radii of curvature.

5. Irradiation device (10; 30) according to claim 4, characterized in that the second elongated reflector (23a, 23b) in a to the first longitudinal side (24) of the first elongated reflector (21) adjoining a first region (40) has a smaller one Has a radius of curvature than in a second region (41) which adjoins the first region.

6. Irradiation device (10; 30) according to one of claims 1 to 5, characterized in that the second elongated reflector (23a; 23b) has no kinks.

7. Irradiation device (10; 30) according to one of claims 1 to 6, characterized in that the highly reflective material of the second elongated reflector 23a; 23b) is evaporated directly onto a reflector element (50) provided with cooling fins (51).

8. Irradiation device (10; 30) according to claim 7, characterized in that the reflector element (50) is an aluminum extruded profile.

9. Irradiation device (10; 30) according to claim 7 or 8, characterized in that the highly reflective material of the second elongated reflector (23a; 23b) is a dichroic material.