IRRADIATION DEVICE FOR INTRODUCING INFRARED RADIATION INTO A VACUUM PROCESSING CHAMBER USING AN INFRARED EMITTER CAPPED ON ONE END

Abstract

An irradiation device for introducing infrared radiation into a vacuum processing chamber has an infrared emitter capped on one end and including an emitter casing tube in the form of a round glass tube, of which a closed end projects into the vacuum processing chamber. A vacuum feedthrough holds the emitter casing tube and leads it in a gas-tight manner through an opening of the vacuum processing chamber. A heating filament and a current return are arranged in the emitter casing tube, wherein the heating conductor has, in the section of the emitter casing tube surrounded by the vacuum feedthrough, a connection element that is led out from the emitter casing tube. The connection element of the heating conductor is guided through a tube section and the return conductor has, in the section of the emitter casing tube surrounded by the vacuum feedthrough, a means for compensating for thermal expansion.

Claims

1-11. (canceled)

12. Irradiation device for introducing infrared radiation into a vacuum processing chamber, having an infrared emitter capped on one end and comprising an emitter casing tube in the form of a round tube made of glass, of which a closed end projects into the vacuum processing chamber, and having a vacuum feedthrough for holding the emitter casing tube and leading it in a gas-tight manner through an opening of the vacuum processing chamber, wherein a heating conductor constructed as a heating filament and a return conductor constructed as a current return are arranged in the emitter casing tube, wherein the heating conductor has, in the section of the emitter casing tube surrounded by the vacuum feedthrough, a connection element that is led out from the emitter casing tube, wherein the connection element of the heating conductor is guided through a tube section and the return conductor has, in the section of the emitter casing tube surrounded by the vacuum feedthrough, a means for compensating for thermal expansion.

13. Infrared emitter according to claim 12, wherein tube section through which the connection element of the heating conductor is guided is constructed as a quartz glass tube and the connection element of the heating conductor is constructed from a wire made of molybdenum or from a molybdenum connection.

14. Infrared emitter according to claim 12, wherein the means for compensating for thermal expansion of the return conductor is constructed as a spring element.

15. Infrared emitter according to claim 14, wherein the spring element is constructed in the form of a wire winding, which is wound about the tube section of the connecting element of the heating conductor.

16. Infrared emitter according to claim 14, wherein the means for compensating for thermal expansion of the return conductor and the return conductor are constructed in one piece as a wire made of molybdenum or a molybdenum compound.

17. Infrared emitter according to claims 12, wherein the means for compensating for thermal expansion of the return conductor is constructed as a sliding bearing made of carbon and has at least two electrically conductive sliding bearing elements in sliding contact with each other, wherein one of the sliding bearing elements is constructed as a sliding bar and the other sliding bearing element is constructed as a sliding bushing.

18. Infrared emitter according to claim 12, wherein, in the closed end of the emitter casing tube, a support element is guided, which is connected to the heating conductor.

19. Infrared emitter according to claim 18, wherein the support element is constructed as a bar made of molybdenum or a molybdenum compound, which is guided in the closed end of the emitter casing tube aligned with the heating conductor.

20. Infrared emitter according to claim 19, wherein the bar made of molybdenum or a molybdenum compound is connected to the heating conductor in a positive-locking or material-bonding fit and the guidance in the closed end of the emitter casing tube is realized by a crimping of the emitter casing tube.

21. Infrared emitter according to claim 12, wherein the return conductor is guided in the section parallel to the heating conductor in a quartz glass tube.

22. Infrared emitter according to claim 21, wherein the heating conductor is supported by at least one spacer relative to the inner wall of the emitter casing tube on one side and relative to the return conductor guided in the quartz glass tube on the other side.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0038] The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

[0039] In the drawings:

[0040] FIG. 1 a first embodiment of the infrared emitter for the irradiation device according to the invention having a return conductor with spring element,

[0041] FIG. 2 an alternative embodiment of the infrared emitter having a return conductor with sliding bearing in the area of the vacuum feedthrough,

[0042] FIG. 3 a detail view from section A of FIGS. 1 and 2 having a support element on the closed end of the emitter casing tube,

[0043] FIG. 4 a spacer for use in the infrared emitter.

DETAILED DESCRIPTION OF THE INVENTION

[0044] FIG. 1 shows schematically an infrared emitter 1 having an axial-symmetric emitter casing tube 2 made of quartz glass having round cross section (outer diameter 19 mm). The infrared emitter 1 is held by a vacuum feedthrough 3, which comprises a sealing ring 4 and a type of gland 5, in the opening of a vacuum processing chamber and projects with its closed end into the vacuum processing chamber. The IR emitter 1 is designed for an operating temperature above 800 C.

[0045] In the emitter casing tube 2 there is a coil-shaped heating conductor 6 (heating filament) made of tungsten having a (heated) length of 140 cm and a return conductor 7 (current return). The return conductor 7 is guided parallel to the heated area of the heating conductor 6 in a quartz glass tube 8. In the area of the closed end of the emitter casing tube 2, the heating conductor 6 and return conductor 7 are connected to each other by a short connecting piece 9. Furthermore, a support element 10 is located there, which represents a holder for the heating conductor 6 and which is fixed in the emitter casing tube 2.

[0046] In the section of the emitter casing tube that is in the area of the vacuum feedthrough 3, a short tube 11 of 60 to 80 mm length made of quartz glass is pushed onto the connection element 12 of the heating conductor 6, which greatly reduces the heat transfer to the seal 4 of the vacuum feedthrough 3. In the area of the vacuum feedthrough 3, due to the tube 11 made of quartz glass pushed onto the connection element 12, the temperature is below approximately 250 C., while the heating conductor 6 reaches temperatures of up to 2500 C. in the area of the usable length of the IR emitter. On the heating conductor 6 and on the return conductor 7, electrical connection elements 12, 12 are welded, which are guided out of the emitter casing tube 2 via crimped sections 13 lying outside of the vacuum feedthrough 3 to a not-shown connector base.

[0047] The return conductor 7 has, in the area of the vacuum feedthrough 3, a spring element 14 in the form of a wire coil. The wire coil comprises up to eight windings on an axial length section of 15 mm and is wound about the short quartz glass tube 11 that is pushed onto the connection element 12 in this section of the heating conductor 6. Due to the wire coil the thermal length expansion of the return conductor 7 is compensated for, whereby an expansion of 8 mm results from operation of the IR emitter at 2500 C.

[0048] FIG. 2 shows only the area of the IR emitter 1 lying in the area of the vacuum feedthrough 3. In contrast to FIG. 1, the means for compensating for the thermal expansion is not a spring element, but instead a sliding bearing 15 made of a high-purity technical carbon, which is connected to the return conductor 7. The sliding bearing 15 is a friction-supported distance compensating element having a sliding bushing 16 with two passage holes that each hold, in pairs, a sliding bar 17 made of molybdenum in sliding fit H7/h7. The sliding bars have a diameter of 1.4 mm. One sliding bar is connected by welding to the molybdenum wire of the return conductor 7 and the other sliding bar is also connected by welding to the electrical connection element 12 of the return conductor 7, which is led out from the end of the casing tube 2. To compensate for the difference in the diameter of the molybdenum wire of the return conductor 7 (wire diameter approximately 0.9 mm) relative to the molybdenum bar of the sliding bearing (diameter 1.4 mm), the molybdenum wire is wound at the welding point with a few turns on the sliding bar and then welded. The ends of the sliding bars opposite the molybdenum wire connection of the return conductor 7 and the connection to the connection element 12 project out of the sliding bushing part and are provided with a thicker section 18, which prevents the sliding bars 17 from sliding out of the sliding bushing 16. The sliding bearing 15 forms an electrically conductive component between the return conductor 7 and the connection element 12, which permits a force-less compensation of the length expansion of the return conductor 7 during operation. The length compensation here takes place without a spring effect just by a material-bond fit, and conductive, sliding contact of the sliding elements with each other.

[0049] In FIG. 3 the section A of FIG. 1 with the closed end of the emitter casing tube 2 is shown in a detailed view. A support element 10 constructed as a round bar made of molybdenum is fixed in the glass wall of the casing tube 2 by a crimped section 13.1 [sic 21]. In addition, the bar is held by a support coil 19 adapted to the inner diameter of the emitter casing tube 2 and contacts the inner wall of the casing tube 2. The diameter of the bar is 0.875 mm and is adjusted so that it can be inserted into the windings of the heating filament 6 with a positive (form) fit. The bar is designed so that the heating filament 6 does not sag, even in the event of thermal expansion and the associated loss of stiffness, but instead is guided in an essentially aligned manner, that is, remains in its radial position. In this way, the risk is minimized that thermal expansion will cause the heating filament 6 to contact the return conductor 7 in this section and thus cause a short circuit. Further in FIG. 3, a connection piece 9 can be seen between the heating conductor 6 and return conductor 7, which, in this case, is a wire piece made of molybdenum having a few windings at both ends, which are welded to the heating conductor 6 and to the return conductor 7. As the connection piece 9, however, there is also a straight wire without windings or another sheet metal part that can be used, which is welded to the heating conductor or return conductor and which fulfills the corresponding electrical requirements.

[0050] FIG. 4 shows a cross section through the emitter casing tube 2 in the area of the heated length, where multiple spacers 20 made of tantalum are provided for the purpose of the exact positioning of the heating conductor 6 and return conductor 7 in the emitter casing tube 2. The spacer 20 is supported relative to the inner wall of the emitter casing tube 2 on one side and relative to the return conductor 7 guided in the quartz glass tube 8 on the other side, wherein the spacer 20 has a guide slot 25 and an open, circular cutout 22. The heating conductor 6 is guided in the guide slot 25 and the open, circular cutout 22 holds the quartz glass tube 8 surrounding the return conductor 7. In this way, the heating conductor 6 and the quartz glass tube 8 guiding the return conductor 7 are held at a safe and reliable distance from each other and from the inner wall of the emitter casing tube 2. The spacer 20 is held on the inner wall of the emitter casing tube by small glass bumps or knobs 23 that fix the spacer 20 especially for the vertical use of the IR emitter at a certain position along the longitudinal axis of the emitter. One or more spacers of this type ensure, even for long emitters, proper guidance, especially of the heating conductor, over the length of the emitter.

[0051] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.