FI89641B - Radiation source and its use in an analyser - Google Patents

Description

1 89641 Radiation source and its use in an analyzer

The object of the invention is to improve a generally known incandescent lamp used as a source of radiation and in particular infrared radiation, so that the lamp is made mechanically stable without deteriorating the radiation efficiency. The invention further relates to the use of such a radiation source emitting electromagnetic radiation in an analyzer.

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Usually, the infrared radiator is based, for example, on a ceramic body around which a resistance wire is wound. No further attempt has been made to attach the resistance wire to the body. When an electric current is applied to such a wire 15 freely wound around the body, the wire acts as a source of radiation and is heated at the same time. The efficiency of the radiator is high when the highest possible radiation intensity per input wattage is obtained in the desired wavelength range.

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The problem with the above solution is that the mechanical dimensions of the radiator change as the wire temperature changes. As the mechanical dimensions change, the focus of the radiation also changes, which in turn causes a change in the optical balance in the analyzer.

This problem is e.g. in a quartz plate lamp, an attempt was made to solve it by evaporating a resistor on the surface of a quartz plate. However, this structure, like other similar ones, has a problem of degraded efficiency, since some of the electrical power is dissipated away from the resistor due to either the support or the surrounding air.

The object of the present invention is to eliminate the above-mentioned '35 problems. The object of the invention is to provide a mechanically stable radiation source and in particular an infrared radiation source without compromising the radiation efficiency. It is a further object of the invention to provide a radiation source for use in an analyzer.

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The characteristic features of the radiation source according to the invention are given in the appended claims.

The invention is based on the fact that the resistance wire is wound on a body 10 with at least two grooves to prevent the wire from moving, e.g. due to thermal expansion or mechanical shock. This achieves both mechanical stability and a "loose" structure that minimizes heat conduction away from the filament.

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The invention will now be described in more detail with reference to the accompanying patent drawings, in which Figure 1 shows a perspective view of a radiation source according to the invention, Figure 2 shows an alternative radiation source according to the invention to Figures 1.

In the figures, the filament 1 is wound around the body 2. The body is preferably made of a ceramic material. Inside the body there is a cavity 3 for guiding the filament wound around the body back to the same attachment point from which the filament is drawn around the body. One attachment point is preferred to minimize thermal conduction losses.

According to the invention, grooves 4 are made in the surface of the body so that the filament wound around the body is pressed into the grooves which hold it in place 35 regardless of thermal expansion and vibrations.

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In Fig. 1, the grooves are made only in the sharp edges 5 of a body of rectangular cross-section. The grooves are not necessarily required at all angles when the filament 5 is rotated around the body part by one turn. A groove at one angle is sufficient. There is also no need to have a groove every round. However, it is advantageous to place the groove at least at the beginning and end of the body part.

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In Figure 2, the grooves 4 are made only at the beginning and end of the body, i.e. preferably at the point where the winding starts and ends.

It is further advantageous to place the body 2 in a quartz tube, which is not shown in the figures. The quartz tube prevents harmful air rotation around the filament 1 and asymmetrical cooling caused by the air.

The invention is in no way limited to the embodiments shown in connection with the figures, but various details of the invention may be modified within the scope of the claims.

Claims (8)

An electromagnetic radiation emitting radiation source consisting of a body (2) and around the wound filament (1), characterized in that the body (2) comprises at least two rafters (4) to prevent the filament (1) from being moved; and that the filament (1) runs along the rafter (4) so that it does not touch the body of the region between the rafters. Radiation source according to claim 1, characterized in that in the interior of the body (2) there is a cavity (3) through which the filament wrap (1) wound around the body is connected to the same attachment point from which the winding of the filament around the body (2) begins. Radiation source according to any of the preceding claims, characterized in that the body (2) around which filaments (1) are wound is arranged in a quartz tube. Radiation source according to any of the preceding claims, characterized in that the body (2) is angular in section. Radiation source according to any of the preceding claims, characterized in that the starting and ending ends of the winding are arranged in the rafter. Radiation source according to any of the preceding claims, characterized in that at least two rafters (4) are located in the frame (2) which is angular in section. Radiation source according to any of the preceding claims, characterized in that it emits infrared radiation. Use of radiation source according to claim 1 in an analyzer.