JPS5925970B2 - photometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photometer, and particularly to a photometer having a light source device suitable for measuring a test sample with excellent measurement accuracy.

In recent years, there has been an increasing demand for highly accurate quantitative analysis of microscopic turtle components in samples, and high-sensitivity analysis has become one of the important factors determining the performance of analytical equipment.

For example, a photometer used as a detector for a liquid chromatograph is required to have noise of 1% or less at O, 005 AUFS (absorbance full scale). Recent advances in electronics have made it possible to obtain highly stabilized power supplies, and other signal processing systems have also become able to obtain high signal-to-noise ratios.

However, in photometers, even if the electrical system is of very high performance, it is still difficult to reduce noise to the above level. The reason for this is that the light intensity from the light source cannot be stabilized to the required degree. The inventors have discovered that the heat generated by the light emitting tube itself is a factor that impairs the stabilization of light intensity.

In other words, the heat generated by the tube increases the ambient temperature of the tube,
It was observed that the irregular fluctuations caused by the air flow around the tube reduced the stability of the light intensity. One possible way to reduce the influence of airflow is to make the light source chamber a sealed structure as shown in FIG.

However, the closed structure has the following drawbacks. First, since the light source chamber is sealed, the temperature rises significantly, which accelerates the deterioration of the light source. Second, this heat lengthens the time it takes for electronic components to stabilize, causing drift. Thirdly, there is a drawback that mechanical parts constituting the optical system are distorted due to heat. Even a sealed structure cannot prevent the fluctuation phenomenon. FIG. 1 is an explanatory diagram of a light source chamber of a conventional photometer.

Light 2 emitted from the tube 1 enters a spectroscope 3 and is irradiated onto a test sample. A large number of ventilation holes 5 are provided in the light source chamber cover 4. In such a configuration, air circulates freely, and fluctuations in the air have a large effect on instability of light intensity. FIG. 2 is an explanatory diagram of a closed type light source chamber. A tube 1 is placed in a sealed chamber formed by a base 14 and a light source chamber cover 6, and this tube is mounted on a mounting base 13 fixed to the base 14. The cover 6 is provided with a window 7 for directing the light beam 2 to the spectrometer 3. In such a configuration, the temperature inside the light source chamber becomes high and convection occurs within the light source chamber. The present invention has been made in view of the above points, and its purpose is to obtain stable light intensity,
The object of the present invention is to provide a photometer that can achieve highly sensitive measurements.

A feature of the present invention is a photometer equipped with a light emitting tube and a means for detecting light from the sample by irradiating light from the tube onto a test sample. At least the outer surface above the light emitting point is tightly adhered with a good thermal conductor,
This thermal conductor is thermally connected to a heat dissipation member to enable highly sensitive measurement of a test sample.

In a preferred embodiment of the present invention, a thermally conductive material closely covering the surface of the tube is thermally connected to a heat dissipating member.

As the heat radiating member, the cover itself of the light source chamber or a heat radiating piece protruding from the outside of the cover can be used. The heat dissipating member is also preferably made of a good thermal conductor and has a larger surface area than the covering. For example, metals such as copper, aluminum, zinc, and silver can be used as a good thermal conductor. It is effective if the area of the tube covered by the thermally good conductor is about 20% or more of the entire surface of the tube. The higher the surface temperature of the tube, the easier it is to generate airflow. Since the area around and above the light emitting point of the tube is hotter than the area below, the covering is provided at least substantially above the light emitting point.
However, this does not mean that the entire area of the outer surface of the bulb located around and above the light emission point is closely covered, but only a part of the outer surface is possible. With such a configuration, the temperature of the tube can be brought close to room temperature or the temperature of the outside air. Examples based on the present invention will be described below.

FIG. 3 is a schematic diagram of the main parts near the light source chamber of an embodiment of the present invention. A closed type light source chamber is formed by a light source chamber cover 16 having a window 17 for taking out light toward a spectrometer or a sample chamber (not shown) and a base 14. A mounting bracket 13 fixed to a base 14 is provided with a fitting 12, and a discharge tube, for example, a deuterium discharge tube 31, is attached to this fitting 12.
is held by. A lighting section 32 is located near the light emission point 35 of the discharge tube 31 in a portion facing the window 17 side. The cover 16 is made of a thermally conductive material. A band 9 made of metallic copper is tightly wound around the outer wall surface near the middle and upper part of the discharge tube 31, leaving a lighting section 32. A part of the band 9 forms a thermally conductive part 11 and is connected to a cover 16 at a connecting part 10 . Light radiant point 3
5 also serves as a heat source, so this part has the highest temperature.

The area around and above the light emission point 35 becomes particularly hot. Therefore, by dissipating heat from these tube wall sections, the degree of temperature rise is reduced, and the generation of air currents is therefore greatly reduced. The band 9 attached to the outer surface of the discharge tube 31 also serves to equalize the temperature of the tube wall. Thereby, local temperature differences on the tube wall can be eliminated, and irregular fluctuations in the air near the tube wall can be reduced. The heat of the discharge tube 31 is transferred to the cover 16 via the heat conduction part 11 of the band 9.
conducted to.

The cover acts as a heat sink. Therefore, convection of air within the light source chamber is reduced, and changes in tube wall temperature due to convection are also reduced. FIG. 4 is a diagram comparing the stability of the temperature of the tube wall above the light emission point when a deuterium discharge tube is used in each of the configurations of FIGS. 1, 2, and 3. T1 corresponds to FIG. 1, T2 corresponds to FIG. 2, and T3 corresponds to FIG. 3. Although the temperature at T2 is higher than that at T1, the stability of temperature changes is improved. T3 is lower in temperature than T1, and the stability of temperature changes is improved compared to T2.
Therefore, even more sensitive measurements are achieved. By the method shown in Figure 3, a stability of 1X1'5 was achieved. In the embodiment shown in FIG. 3, an extension of a bendable copper band was used as the heat conduction part as shown in FIG. Since the position of the discharge tube 31 is determined optically, it is difficult to change the position when attaching a good thermal conductor. In addition, light source chamber cover 1
6 cannot easily change locations either. Therefore, it is preferable that the part connecting the adhered part made of a good thermal conductor to the light source chamber cover or the heat sink has flexibility. By making the length of the heat conductive part expandable and retractable, installation becomes extremely easy even if the distance between the discharge tube and the cover changes somewhat. Fig. 6 and Fig. 7 show modified examples of the heat conductor. A conductive plate 18 is provided. Thermal conductors are not limited to plate-shaped ones,
For example, a cloth-like material, a braided wire, etc. can also be used. FIG. 8 is a diagram showing a schematic configuration of the vicinity of the light source chamber of a photometer according to another embodiment of the present invention. A light source chamber cover 21 having a light extraction window 11 is provided with ventilation holes 25 and 26. A blower or exhaust fan 23 is provided near one of the ventilation holes 26. A tube 20 made of a discharge tube or a filament lamp is disposed inside the light source chamber. Almost the entire glass surface of the bulb 20 is tightly covered with a covering face 28 made of a good thermal conductor. A plurality of heat radiation protrusions 22 are provided on the outside of the covered face piece 28. The heating protrusion 22 is also made of a good thermal conductor. The lighting section 27 of the bulb 20 is placed in a tube 29 so as not to be exposed inside the light source chamber. The end of the tube 29 is in contact with the window 17. tube 20
After passing through the window 17, the emitted light is made monochromatic by a dispersion element or an optical filter, and then irradiated onto the sample.

The light transmitted through the sample is detected by a photoelectric detector, and the concentration of components in the sample is determined. Cooling air is forced into the light source chamber by a fan 23. The air that has removed heat from the bottom of the covered facepiece 28 and the protrusions 22 is discharged from the ventilation holes 25. Since the covered facepiece is made of a good thermal conductor, there are no local differences in temperature on the bulb surface, and the overall temperature approaches room temperature. Therefore, since the space within the tube 29 has almost no fluctuation, the intensity of the extracted light is stabilized. Further, according to experiments, in the case of a discharge tube, changes in the tube wall temperature affect the stability of the luminous intensity, but this embodiment can also reduce such an effect. By reducing the influence of heat, stable luminescence intensity can be obtained, and it has become possible to achieve even higher sensitivity detection, for example, 0.005 AUFS with noise of 1% or less. Furthermore, effects such as an improvement in the life of the tube and a reduction in drift are brought about. As explained above, according to the present invention, a photometer suitable for high-sensitivity measurement can be obtained, and its effects are enormous.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a light source chamber of a conventional photometer, Fig. 2 is an explanatory diagram of a closed type light source chamber, Fig. 3 is a diagram showing a schematic configuration of main parts of an embodiment based on the present invention, and Fig. 4 Figures 1, 2 and 3 respectively are diagrams comparing the stability of the tube wall temperature, Figures 5 to 1 are diagrams showing examples of the shape of the heat conductor, Figure 8 The figure is a diagram showing a schematic configuration of main parts of another embodiment based on the present invention. Explanation of symbols, 1, 20...Tube, 3...Spectroscope, 9
... Band, 11, 18, 19 ... Heat conduction plate, 16
, 21... Light source room cover, 17... Window, 22...
Heat dissipation projection, 23-... Fan, 25, 26... Ventilation hole, 27, 32... Lighting part, 28... Covered facepiece, 2
9...Cylinder, 31...Discharge tube, 35...Light emission point.

Claims (1)

[Scope of Claims] 1. A photometer comprising a light emitting tube and a means for detecting light from the sample by irradiating the light from the tube onto the test sample, A photometer characterized in that a good thermal conductor is closely attached to at least an outer surface substantially above a light emission point among the surfaces, and the good thermal conductor is thermally connected to a heat radiating member. 2. The photometer according to claim 1, wherein the heat radiating surface area of the heat radiating member is larger than the contact area of the good thermal conductor with the bulb. 3. In a photometer equipped with a tube that emits light and means for detecting the light from the sample by irradiating the light from the tube onto the test sample, at least the light emitting portion of the outer surface of the tube is provided. A good thermal conductor is closely attached to the outer surface substantially above the point, the good thermal conductor is thermally connected to a heat radiating member, and the heat radiating member forms a chamber that isolates the entire bulb from the outside air. Features photometer.