Chemistry: molecular biology and microbiology – Apparatus – Including measuring or testing
Patent
1998-05-23
2000-10-17
Beisner, William H.
Chemistry: molecular biology and microbiology
Apparatus
Including measuring or testing
435 30, 435 34, 4352863, 4352873, 4353091, C12M 126, C12Q 124
Patent
active
061330205
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to an apparatus for determining the number of microorganisms in air, with a device for the settlement of microorganisms, said device having a lower part and a cover, a nutrient or culture medium being located in the interior of the settlement device and to a method for operating this apparatus.
2. Prior Art
To detect the number of microorganisms, in particular germs, such as fungae, bacteria, etc., in air, it is known to cause germs suspended in the air to settle on a culture medium during a predetermined timespan. This culture medium is then covered and exposed to conditions which are conducive to the reproduction of the settled germs. After a predetermined timespan has elapsed, seats or zones on the culture medium which result from the growth of the settled germs are counted.
A so-called Petri dish, which has a lower part with a nutrient medium as well as a cover, is used for carrying out this method. The cover is removed from the lower part and the Petri dish is left open during a desired timespan. The Petri dish is then closed again by hand. The accuracy of this way of measuring the number of germs in air depends largely on the carefulness of the person who carries out these measurements manually. Moreover, this previously known method makes it necessary for the person carrying out such measurements to be present during the entire measuring operation. This is unfavorable, in particular, when such measurements have to be carried out outside the usual work time, in a place where access is difficult, etc.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention is to eliminate said and further disadvantages of the prior art.
Embodiments of the present invention are explained in more detail below with reference to the accompanying drawings in which:
FIG. 1 shows a side view of a first version of the present apparatus,
FIG. 2 shows a top view of the apparatus from FIG. 1,
FIG. 3 shows a side view of a second version of the present apparatus,
FIG. 4 shows a top view of the apparatus from FIG. 3,
FIG. 5 shows the mechanical part of the present apparatus partially in a vertical section,
FIG. 6 shows a top view of the lower portion of the mechanical part from FIG. 5,
FIG. 7 shows a block diagram of the electrical part of the present apparatus,
FIG. 8 shows a correlation table, and
FIGS. 9 to 14 show a second actuating arrangement.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
FIG. 1 shows a side view of a first version of the present apparatus, whilst FIG. 2 shows a top view of the apparatus from FIG. 1. This apparatus serves for determining the number of germs in air, and it comprises a device 1 for the settlement of germs and an arrangement 10 for actuating this settlement device 1.
The settlement device 1 is designed, in the present case, as a Petri dish known per se. The Petri dish 1 has a lower part 3 (FIG. 5) and a cover 5. The top side of the floor of the dish lower part 3 is covered with a culture or nutrient medium 4, on which microorganisms can settle when the Petri dish is open. The settled microorganisms can then reproduce on the nutrient medium 4 when the Petri dish 1 is closed. The culture medium 4 advantageously lies in a horizontal plane.
The settlement device 1 is designed, furthermore, in such a way that germs or particles can no longer pass into this device 1 during the incubation time. For this purpose, the cover 5 of the Petri dish 1 is designed in such a way that its edge part 6 hanging down also prevents germs from passing onto the lower part 3 during the incubation time. In this case, the cover 5 can rest on the upper edge of the dish lower part 3 either sealingly or so as to leave a gap between the cover 5 and the lower part 3. In order to form this gap, the underside of the dish cover 5 is provided with projections in a way known per se.
The actuating arrangement 10 comprises a housing 11 which has a horizontally extending upper wall 12, a display or
REFERENCES:
patent: 3001914 (1961-09-01), Andersen
patent: 4468914 (1984-09-01), Pestes
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