DE102010052870A1 - Arrangement for detecting level of medium, particularly fluid in container, has area for receiving container with medium introduced in interior of container - Google Patents

Abstract

The arrangement has an area for receiving a container with a medium introduced in an interior of a container. A transmitting unit is arranged at a side of the receiving area for the container for providing a transmission light. The transmitting unit has a source area for transmission light, such that transmitted light coming out from the source area enters with a divergent radiation pattern in a container. An independent claim is also included for a method for detecting a level of medium in a container.

Description

The present invention relates to an arrangement and a method for detecting levels in a container, for example in a test tube or ampoule.

Background of the invention

Glass tubes, such as test tubes or ampoules, which are often referred to as sample tubes, are used in particular in medicine for the examination of samples. Blood is an example of such a sample. To analyze the blood, the blood is placed in a sample tube and then preferably centrifuged so that a separation of the blood components according to their density in the sample tube. The constituents of the blood are, in particular as phases, arranged or distributed in layers in the sample tube. The separated components of the blood can each be present as a liquid or else as a less liquid medium, for example as a gelatinous mass. The separated components of the sample to be examined are therefore generally referred to as media. The constituents may consist, for example, of blood serum, separating gel (a gel which is already contained in the vacuumed glass tube before the blood is taken) and blood cake, and optionally also other media in addition, or also of blood serum and blood cake or of blood plasma and a separated part the cellular components of the blood.

The components of the blood are generally well separated. There are quite clear interfaces or interfaces between the different liquids or media. In particular, for the removal of the components of the blood or generally for the separation of the components, it is necessary to know the level of the respective components in the sample tube.

The liquids or media can be completely transparent or absorbent. To make matters worse, that on the sample tube, for example on a glass tube, an empty or printed label is applied, which surrounds the sample tube in whole or in part.

Various methods are known for detecting and / or determining the fill levels and / or the interfaces.

A first approach is based on a one-way photoelectric sensor with a fine beam, such as a laser photoelectric sensor. In doing so, the beam penetrates through the media with refraction of light at the surfaces. At the media interfaces disturbances occur in the amount of light received. These disturbances can be recognized as interfaces.

A further development of this type of surveying is based on a one-way light barrier with a fine beam and a selected wavelength. In known liquids, the different absorption of the emitted light can be evaluated. The transmitted amount of light changes depending on the medium. The change in signal strength indicates the media change.

The latter can be further developed by several different wavelengths successively illuminate the glass tube and its media. The absorption is again differently distributed among the different media with a favorable selection of the wavelengths.

Similarly, a light beam may be used with white light or with broadband light (in the UV, visible or IR range) or with light consisting of several different wavelengths. The transmission of light through the various media is monitored by a spectrometer. From the transmission behavior of different wavelengths can be closed to the medium and the transition between different transmission behavior on the level.

Using a matrix camera, image processing and diffused lighting, the interfaces between the media appear as dark stripes. These can then be evaluated.

Another method is based on a measurement by means of ultrasound. In a defined, for example, level, bottom of the glass tube, an ultrasound beam can be coupled from below into the glass tube and the time successive incoming echoes of the various interfaces are measured.

All above-mentioned methods for level detection prove to be particularly disadvantageous or not useful as soon as a label is applied to the sample tube, the last method because of the variety of variants of the glass tubes.

A laser-type through-beam sensor is considered impossible with applied, strongly light-scattering label. The parallel or well-defined light beam is destroyed by the label.

In an absorption-based method, the label causes similar problems because the transmission is massively changed by the label. A statement with only one light source with only one wavelength is thus no longer possible, especially if the label is once applied, not another time.

A spectroscopic measurement seems possible, but is considered quite expensive and also considered slow.

A solution based on the 2-dimensional image and diffused lighting is even impossible with labels applied (see for example 1 : The air-oil interface becomes invisible behind the label).

The ultrasound solution can fail if the bottom of the glass tube is not sufficiently defined, because then no ultrasound beam can be injected efficiently and defined.

General description of the invention

Against this background, the present invention has the object to provide an arrangement and a method for detecting levels in a container, which at least reduce the disadvantages of the prior art described above.

It should be possible in particular to measure the level of the topmost and / or the different liquids or the more or less liquid media in a sample tube.

In particular, this should still be possible if an empty or printed label is applied to the sample tube, which completely or only partially surrounds the sample tube.

It should be possible to detect or measure completely transparent or absorbing media.

Finally, the level detection should also be economically feasible in terms of cost.

The stated objects are achieved by an arrangement and a method according to the two independent claims.

Advantageous embodiments are the subject of the respective subclaims.

• – einen Bereich zur Aufnahme eines Behälters mit wenigstens einem in einem Innenraum des Behälters eingebrachten Medium,
• – eine Sendeeinheit zum Bereitstellen eines Sendelichts, welche an einer Seite des Aufnahmebereichs für den Behälter angeordnet ist,
• – eine Empfangseinheit für das Sendelicht, welche an einer der Sendeeinheit gegenüberliegenden Seite des Aufnahmebereichs für den Behälter angeordnet ist,
• – wobei die Sendeeinheit derart zu dem Aufnahmebereich angeordnet ist, dass ein im Aufnahmebereich positionierter Behälter im Wesentlichen quer, vorzugsweise senkrecht, zu seiner Längsachse mittels des Sendelichts durchleuchtbar ist, wobei

vorzugsweise die Sendeeinheit einen Quellbereich für das Sendelicht an dem Aufnahmebereich für den Behälter definiert, so dass das Sendelicht ausgehend von dem Quellbereich mit einem divergenten Strahlungsverlauf in den Behälter eintritt.First, in the present application, an arrangement or device is claimed for detecting and / or detecting at least one level of a medium, preferably a fluid, in a container. This includes the following components:

• A region for receiving a container with at least one medium introduced in an interior of the container,
• A transmitting unit for providing a transmission light which is arranged on one side of the receptacle for the container,
• A receiving unit for the transmitted light, which is arranged on an opposite side of the transmitting unit of the receiving area for the container,
• - Wherein the transmitting unit is arranged to the receiving area such that a container positioned in the receiving area is substantially transversely, preferably perpendicular, transilluminable to its longitudinal axis by means of the transmitted light, wherein

Preferably, the transmitting unit defines a source region for the transmitted light at the receiving region for the container, so that the transmitted light enters the container starting from the source region with a divergent course of radiation.

Within the scope of the invention is also a method for detecting at least one level of a medium in a container by
the container is transilluminated with a transmitted light substantially transversely, preferably perpendicular, to a longitudinal axis of the container, wherein
the transmitted light in the interior of the container, preferably at least in sections, a starting from an inlet side into the container in the direction of an outlet side of the container substantially divergent beam characteristic.

The arrangement according to the invention is preferably suitable for carrying out the method according to the invention. The inventive method is preferably carried out by means of the inventive arrangement.

The receiving area defines a space in which the container is positioned during level detection. For example, the receiving area can be provided by a kind of opening and / or a type of holder in or on a device which contains the transmitting unit and the receiving unit.

The container is preferably a tube or glass tube, such as a test tube, an ampoule or generally a sample tube. Basically, other containers are conceivable. It is not limited to glass tubes alone. The vessel should have a smooth, transparent wall on the inlet side and the outlet side.

The transmitted light penetrates transversely or substantially transversely through the glass or the side wall of the container into the interior of the container and into the in the container arranged media. In general, the transmitted light enters horizontally. The transmitted light occurs preferably strongly divergent.

A divergent beam characteristic or a divergent radiation profile is characterized in that the transmitted light runs away from a center, preferably substantially radially, to the outside. The center is defined by a source region for the sensor light, ideally by a source point. For characterization, the opening angle of the beam path or the provided beam cone can be used. The opening angle at which the transmission light is provided is preferably in a range of greater than 30 °.

In one embodiment, the source region for the sensor light is provided directly or directly by a light source, in particular by the light-emitting side or light exit side of a light source.

The arrangement here is characterized in that the transmitting unit comprises a light source, which defines the source area for the transmitted light. The light source is disposed on a side of the container where the transmitted light enters the container. The light source is preferably positioned directly on the entry side for the transmitted light on the container.

In a direct positioning of the light source on the inlet side, the light source is arranged at a distance of less than about 8 mm, preferably less than about 3 mm, to the inlet side of the container.

In a further embodiment, the light source is not directly positioned but at a distance from the entrance side.

For this purpose, the transmitting unit comprises a light source and an optical component, wherein the transmitted light can be focused by means of the optical component on one side of the container, at which the transmitted light enters the container, wherein the above-described source region for the transmitted light here the image (focus) of the corresponds to optical component and is preferably defined by the focus.

In general, the focus is at a distance of less than about 8 mm, preferably less than about 3 mm, inside or outside the entrance side or side wall of the container where the transmitted light enters the container. The focus is preferably directly on the inlet side of the container. In particular, the transmitted light in focus has a broadcasting spot having a diameter of less than about 6 mm, preferably less than about 3 mm, or a light gap having a width of less than 6 mm, preferably less than 3 mm.

The values given above are particularly applicable when the container is a glass tube or vessel with a diameter of the order of about 12 mm. In the case of containers with a significantly larger format than the assumed approx. 12 mm diameter, in particular the distances from the transmitting unit to the container and / or from the container wall to the receiving unit can also be greater than the dimensions mentioned.

In a first approach, the dimensions, in particular the distances, are to be increased approximately proportionally to the size or diameter of the container. The values should then be scaled with a value of vessel diameter (or pipe diameter) divided by 12 mm (value · ø / 12 mm).

In a second approach, the dimensions, in particular the distances, are to be increased approximately proportionally to the root of the format ratios. The values should then be scaled with a value of the root of the vessel diameter (or glass tube diameter) divided by 12 mm (value x (ø / 12 mm) ^1/2 ). Preferably, this represents the minimum factor for scaling or zooming.

Preferably, in the two embodiments described above, the transmitting unit adjoins the receiving area for the container or on an outer side of the container.

The light source may be a single light source. But it can also include a variety of light sources. Depending on the embodiment of the invention, the light source may be a substantially punctiform light source or a substantially linear light source. Preferably, the light source is provided by an LED or a plurality of LEDs. It may additionally be arranged a diaphragm between the light source and the inlet side. This is especially to be provided when larger light sources are used. In general, a small transmission source relative to the container is used, in particular seen at least in the longitudinal direction of the container. Preferably, the diameter of the light source or the width of a light slit or spot is less than 40%, preferably less than 10%, of the diameter or transmittance width of the container.

The receiving unit is designed to detect the transmitted light, which is coupled from the transmitting unit into the container, transmitted through the container and the media in the container and coupled out of the container. The receiving unit preferably adjoins the receiving area for the container or to an outside of the arranged in the receiving area container.

In one embodiment, the receiving unit comprises a receiver, which is arranged on one side of the container, at which the transmitted light emerges from the container. In this embodiment, the receiver is arranged as close as possible to the outlet side. Preferably, it is applied directly or directly on the exit side. For example, the receiver may be located at a distance of less than about 8 mm, preferably less than about 3 mm, to the exit side of the container.

In a further embodiment, the receiver is not arranged directly on the outlet side. The arrangement is characterized in that the receiving unit comprises a receiver and an optical component, wherein the receiver is spaced from one side of the container, at which the transmitted light emerges from the container, and the light emerging from the container by means of the optical component can be mapped to the recipient.

The receiver can be provided by at least one, preferably 1-dimensional or 2-dimensional, image sensor and / or by at least one brightness sensor. An example of an image sensor is a CCD camera. An example of a brightness sensor is a photodiode.

The optical component for imaging the transmitted light emerging from the container can be provided by at least one lens, an objective and / or a lens array, preferably a CIS lens array (contact image sensor). Preferably, the array consists of or comprises the array of GRIN lenses (gradient index lenses). In one embodiment, the optical component is suitable for imaging the preferably curved exit surface onto the receiver.

In a further embodiment of the invention, the arrangement comprises an amplifier, a device for controlling the exposure time and / or the amplification and / or a device for controlling the transmission power. As a result, the transmitted light received by the receiver can be amplified and / or the exposure time for irradiating the container can be extended and / or the transmission power for irradiating the container can be increased such that an influence or absorption, in particular by a label disposed on the container, in Substantially compensable.

If brightness sensors are used as receivers, in a preferred embodiment at least two or exactly two brightness sensors are provided. A first brightness sensor is arranged above the transmitting unit and a second below the transmitting unit (with respect to the longitudinal axis of the container).

Generally, the container and the media therein are scanned or scanned. A main scanning direction is transverse, preferably perpendicular, to the media boundaries.

Another scan direction, d. H. the movement along the circumference is perpendicular to the main scanning direction along the vorzugswesie transparent container wall.

For scanning the container and the media located in the container, in one embodiment, the light source and the container, and in particular the receiving unit, or the transmitting unit are moved together with the receiving unit and the container relative to each other. In general, the transmitting unit and the receiving unit are at rest and the container is moved across the media boundaries, typically along the container longitudinal axis relative to the two units. Preferably, the transmitting unit and the receiving unit are rigid with each other and are moved relative to the container. For example, the container may be inserted into the receiving area by a robotic arm and provide the movement to scan the container. As an alternative or supplement to the movement along the longitudinal axis of the container, a movement over the circumference of the container and thus a rotation of the container can take place, so that the container can be scanned along its longitudinal axis and / or over its circumference.

In a further embodiment, the scanning of the container does not take place via a movement of the components relative to one another. For this purpose, the light source is provided by a plurality of individual light sources. These are arranged distributed along the longitudinal axis of the receiving area and in particular of the container and / or over the circumference of the receiving area and in particular of the container. For scanning the container and the media, the individual light sources are switched on and / or switched off in a time-coordinated manner. For this purpose, the arrangement has a device for driving the individual light sources so that they can be switched on and / or off, preferably one after the other, and a preferably pulsed transmitted light along the longitudinal axis and / or over the circumference of the container can be provided for scanning the container.

Preferably, the light source is an IR light source. The light source generally has an emission spectrum that is adapted to the media to be examined. The emission spectrum of the light source or of the light sources is preferably selected so that the transmitted light is not or only slightly absorbed by the media to be examined and the glass wall or is little absorbed in at least one medium and strongly absorbed in another medium. With strong absorption in several media is preferably between these media each a medium with low absorption. If the light source consists of a plurality of individual light sources, in another embodiment the transmitted light is emitted by the different light sources having at least two different wavelengths, which are preferably chosen so that the transmitted light of a first wavelength is at least slightly absorbed in at least one medium and the transmitted light a second wavelength is strongly absorbed in the same medium. A strong absorption is present in particular at an absorption of greater than 80%, preferably greater than 90%. In particular, a weak absorption is present at an absorption of less than 20%, preferably less than 10%. Preferably, the light source emits a transmitted light in a spectral range selected so that the transmitted light is little absorbed in all or in all but one medium.

Finally, within the scope of the invention is also a system for detecting at least one level of a medium, preferably a fluid, in a container. The system comprises an arrangement according to the invention and an evaluation unit which is designed to determine a brightness profile of the transmitted light emitted from the container substantially transversely to the media separation surface.

The present invention will be explained in detail with reference to the following embodiments. For this purpose, reference is made to the accompanying drawings. The same reference numerals in the various drawings refer to the same parts.

1 shows an example filled with water and oil glass tube.

2 shows a schematic representation of the in 1 shown example.

3.a and 4.a schematically show a detailed view of the area Z from 2 in a cross section for a transmitting unit comprising a light source and a lens ( 3.a ) and for a transmitting unit from a light source, which rests against the outside of the container ( 4.a ).

3.b and 4.b schematically show an enlarged detail view of the inlet side into the side wall of the container from the 3.a and 4.a ,

5 to 9 show various exemplary optical simulations for various embodiments.

Detailed description of the invention

For illustration shows 1 a test tube 1 in which, as media down water 2 and above oil 4 are located. They are separated by a clearly recognizable separating surface 3 , The upper parting surface 5 between oil 4 and air 6 is only slightly visible on the top right, most of the separation area 5 However, it is completely obscured by an externally applied label 10 ,

2 shows a schematic representation of the in 1 shown example in an optical simulation. Shown is a glass tube 1 , the uppermost with air 6 is filled. To make the 3D view clear, the tube is 1 slightly skewed. A paper label 10 is on the outside of the pipe 1 attached to the glass tube 1 completely circumnavigated. Etiquette 10 can cover only part of the circumference. As a medium is water 2 intended. It is also an oil-like medium 4 with higher refractive index than water 2 intended. As a small strip is a light source 20 located. The image plane is located directly behind the glass tube 1 , A few rays of transmitted light 23 the optical simulation are shown. The glass tube 1 can also be made of another, transparent material, such. As plastic, exist. The solution according to the invention, which addresses the problems with an applied, highly light-scattering label 10 bypasses and the level measurement through the label 10 through, based on a type of photoelectric barrier.

This has in a first embodiment, the following properties: The transmitted light 23 will be on a small dot or on a horizontal line or on a source area 22 or focus 22 , preferably parallel to the media separation surfaces 3 . 5 and 7 , focused (see 2 and the 3.a and 3.b ). The focal plane is the entrance side 1a or entrance area 1a and thus the side wall of the glass tube 1 , Alternatively, the light can 22 also near the entrance area 1a be generated, the shape of the light spot should be similar (see the 4.a and 4.b ).

The focal plane or the generation of light directly in front of the entrance surface 1a is required, as shown here on the entry side 1a , a label 10 on the glass tube 1 can be applied, which scatters the light strongly. Now if light is generated there with divergent radiation or there is imaged, preferably with a large aperture or an opening angle 24 , preferably at an angle greater than 30 °, the light enters the glass 1 and the subsequent medium 2 and or 4 with strongly divergent angles. A label 10 can this ray of light 23 no longer destroy in the sense that the beam properties of the light beam 23 would be greatly changed. The light rays emerging from the label have substantially the same angular distribution, in particular a little more strongly divergent, and the unchanged apparent light source size. The light-scattering label 10 essentially only changes the light intensity. The jet properties, however, persist.

The light source or transmission source 20 can be from a single light source 20 with the mentioned geometry, preferably as a point or as a horizontal line exist. But it can also be from a larger light source 20 with aperture in front or also from many single, small light sources 20 consist.

The light penetrates by refraction into the glass and then into the medium. After that, it spreads in the medium with strong divergence. Preferably, the transmitted light occurs 23 already in the side wall of the container with a diverging beam characteristic. As an insignificant side effect, the light is reflected weakly on the glass and on the medium.

The light is reflected on a preferably horizontal media separating surface, in particular if the refractive index of the two adjacent media differs sufficiently large (example: oil-water, water-air). In a transition or separation area from a higher to a lower refractive index medium, even total reflection occurs. In this way, the light in the medium, in which the light was coupled directly, preferably through the glass, spreads strong. It almost does not connect to the adjacent medium. The media raceway is also a separation surface for the light.

On the opposite side of the transmitter, the light hits the glass wall again. It is transmitted through the glass wall with quite small reflection losses and leaves the container or vessel. Because of its divergent radiation, the light hits not only exactly opposite the transmitter on the glass wall, but all around. However, there, d. H. the farther away from the side opposite the broadcasting station, the reflections and thus also the reflection losses as they pass through the glass wall become more and more. Again, a label may be attached to the exit point.

The light emerging on the opposite side of the transmission spot is picked up by an imaging sensor, preferably 2-dimensional or 1-dimensional, ie by a matrix or line scan camera. In particular, the vertical brightness profile, that is, evaluated transversely to the media separation surface.

It is necessary that the image sensor is applied substantially directly on the exit surface with a distance as close to zero or alternatively that the exit glass surface of the glass tube with an optic, preferably with a large aperture, is imaged on the image sensor.

This image can be taken with a simple lens or lens, or with a CIS lens array (CIS = contact image sensor). The latter consists of or includes GRIN lenses (gradient index lenses). Thanks to this type of optics, a scattering object such as paper, paper labels or even a thin white plastic label may now be applied or glued to the glass exit surface. Such a label does not significantly alter the received image on the exit surface, but darkens the image a little. If the label is applied over the entire exit surface, the whole picture is a bit darker. This does not bother in any way, since this can be fully compensated with a little more gain, a longer exposure time or a higher transmission power at the transmitter. If the label is only applied over part of the glass tube, there is an additional light-dark transition in the picture. However, this is usually not as strong as the one created by the media raceway. Especially with a large aperture, the influence of a thin paper is not great. The light is scattered in the paper, but thanks to the large aperture, it is still the main object.

In an alternative or supplementary embodiment, the light can also be recorded with one or more brightness-measuring sensors. The requirements for the optics (large aperture) or the arrangement geometry, in which the sensors rest on the glass exit surface or image, is the same as just described. Only the requirement for the optical resolution is lower here. A recommended solution consists of at least 2 such brightness sensors, one mounted slightly above and the other slightly below the opposite transmitter. In this case, it is then possible in particular to work with the difference and the sum and / or the ratio of the two signals and / or with the ratio of the difference to the sum of the signals.

In a first embodiment transmitter and receiver are moved along the glass tube and so scanned or scanned the liquid contents or the media enclosed there with the various media separation surfaces. If, for example, the transmitter-receiver is scanned from top to bottom, then light is first coupled into the air contained in the glass vessel. The closer one approaches the first media separation surface, the clearer the interface appears, only very little light is coupled into this first medium. For this reason, the upper half of the picture appears bright in the picture or in the line picture, the lower one dark. It is dark just below the interface.

Scanning further downwards, the transmitter briefly hits the interface and illuminates the lower medium as well as the upper air. Both are a bit bright. If the transmitter is narrow in the direction of motion, then the coupling is usually poor because the media raceway is often not exactly flat, but at the edges usually slightly curved (because of the surface tension). In addition, this moment of coupling into both media is very short.

Shortly thereafter, the light is only coupled into the medium under the top media separation surface. Now the upper half of the picture is dark in the picture, the lower one is bright. From the transition from the upper half of the picture to the lower half of the picture, the height of the medium is calculated from the scan movement.

If the transmitter and receiver are moved further down, then the dark-bright border in the image continues to move upwards, the middle and large part of the image is now brightly illuminated.

If scanning is continued downwards, further media separation surfaces can be identified in exactly the same way.

It has proven to be advantageous if there is a clear refractive index difference between the media. In this case, the refractive index difference between the media is preferably in a range of greater than 0.05 or greater than 0.1. From a difference of 0.2, such as oil-water, there are very clear images.

It is also advantageous if the diameter of the light source or the width of a light slit or spot is less than 40%, preferably less than 10%, of the diameter or the transmission width of the container. For a typical container diameter of 12 mm, this corresponds to a source size smaller than 5 mm, preferably smaller than 1 mm.

In particular, at a first or second time, the coupling takes place in the medium with the higher refractive index. Because the image when coupled into the medium with a higher refractive index, in comparison to the other side of the interface, a little cleaner. To a large extent, total reflection occurs here. Almost nothing is coupled into the smaller index medium. At the other time, the coupling takes place on the other side of the interface, ie in the medium with the smaller refractive index. Here is a small or minimal coupling into the opposite medium. However, this is minimal because of the refraction away from the solder, in particular very close to the interface, since here the angles of the light beams from the light source to the interface are small. As a result, these light beams are strongly refracted and propagate in the opposite medium at a significantly elevated angle to the interface. Thus, the image area along the opposite medium near the interface remains dark.

In a further embodiment, there is no need for a scanning or scanning movement. This embodiment is simpler to use but requires more effort on the sensor side. Here, on the inlet side of the glass tube with many small LEDs, preferably IR LEDs, or transmitted light sources are used, which are applied along the preferably entire height or the longitudinal axis of the glass tube or at least the vertical area of the various media to be measured well covers.

The LEDs are brought in the simplest case one after the other by a current pulse to light up. From each pulse, a picture or line image is made on the opposite side. The image recorder is preferably also chosen so large that at least the vertical area of the various media to be measured is well covered. In particular, the number and / or the arrangement of the transmitted light sources are selected and / or the image sensor is chosen so large that the media to be measured can be detected.

If the LEDs now flash from top to bottom or vice versa, the result is images that match those of the scanning method. Only the positions of the light-dark changes due to a media interface are no longer in the same position in the picture as before, but always opposite the currently lit LED. However, this solution requires a certain size of the image sensor. In addition, an LED array, here an LED line, instead of a single LED is required. The sensor should be selected larger accordingly.

It is advantageous if the diameter or the width of the individual light sources in the array direction is less than 40%, preferably less than 10% of the diameter or Radiation width of the container. For a typical container diameter of 12 mm, this corresponds to a source size smaller than 5 mm, preferably smaller than 1 mm.

In the case of printed labels, it is recommended to work with near-infrared light sources. Remote IR light sources can also be used. In this area, many printing inks are only weakly absorbent and disturb the image much less. Graphite-based inks or printing particles should be avoided, since they have a broad absorption spectrum and even in the near IR still have strong absorption.

The effect of broadband absorbing printing can be reduced or even minimized in the case of solution with the LED line by rotating the glass tube to make additional measurements around the glass tube. Of course, the entire measurement takes a little longer.

In the case of the scan solution, the additional rotation of the glass tube can also be used. Alternatively or in addition to the rotational movement, an additional improvement can be achieved here with optical means. For this purpose, a receiving optics is selected, which does not image the exit plane of the glass tube but essentially its curved exit surface on the receiver. Further, not only an LED is mounted in the horizontal plane around the glass tube. Instead, several LEDs are arranged. These are preferably each again in direct contact with the glass tube. Or there is an image of the LED spot on the preferably curved entrance surface of the glass tube. In one embodiment, about one third or one half of the glass tube circumference is covered with it.

The LED's can now be successively or optionally also lit together. In the best case, an image is taken, which was exposed by one LED. Now, a printing of the label such. As a barcode or a font, averaged out and thus hidden.

The 5 to 9 show various exemplary optical simulations for various embodiments. The brightness coding can be seen on the right next to it.

The 5 and 6 show first an optical simulation, without a label applied to the glass tube label.

5 shows an optical simulation with light coupling 1 mm above the media interface air-water. The interface between air and water is very clearly visible, the image above the interface is very bright and directly below it is very dark. Further down, ie in the lower quarter of the picture, another spot appears with low brightness. This spot is getting weaker towards the interface.

6 shows an optical simulation with a same representation as above, but with light coupling 1 mm below the media interface air-water. The interface between air and water is again very visible, the picture above the interface is very dark and directly below it is very bright. Here is the light coupling from the water into the air disappearing. The upper part of the picture is totally dark. On the right side of the picture is a simulation with representation of the beam paths shown here but of the boundary water (top, low refractive index) and oil (or heavy oil, bottom, high refractive index). The reflection of the rays, here even total reflection, is clear.

The following 7 to 9 show the results of simulations, which illustrate the influence of paper etiquette.

7 shows the coupling of the light in the middle of the 10 mm thick water layer with an additional paper label, which extends from below to 1 mm below the coupling point. The latter causes a slight brightness change directly below the center of the image. The image illumination is only slightly disturbed by the label.

8th shows the scan image 4 mm higher with a coupling of the light 1 mm below the water-air interface. The label extends back to 1 mm below the light coupling. The image of the water-air interface is undisturbed. Within the bright spot appears a sharp brightness transition, which was created by the label. The basic image structure is unchanged by the etiquette, this can be done with the simulation without labels (see 6 ).

9 shows the scan image again 2 mm higher with a coupling of the light 1 mm above the water-air interface. The label now extends to 1 mm above the light coupling. The etiquette reaches into the bright spot and causes a brightness transition within the spot (here directly above the word "air").

From the simulations and the beam geometry considerations, it can be concluded that in a scan, the transition of light from air to water, or more generally from a higher refractive index to a lower refractive index (or vice versa) results in a paging change: first A bright spot of light appears above the interface, then below. With a label, however, there is no such page break. The upper edge of the label always leads to a weak brightness limit in the image, where it is brighter above the border than below, regardless of whether the light is coupled in above or below the upper edge of the label. The same applies to the lower edge of the label.

In a further embodiment, the invention can be extended even further with the absorption of specific wavelengths: If a medium is precisely known, then the wavelength of the light source can be selected so that this medium absorbs this light very strongly. The light is absorbed, for example, up to 90%, preferably up to 99.5%. In one embodiment of the invention, the light can even be absorbed almost up to 100%.

As a result, in a scan at coupling above the interface, ie when coupled into the non-absorbing medium, an interface appears as a bright spot with sharp boundary at the interface (similar to in 5 ). Below the bright spot, it is totally dark. When changing the coupling into the absorbing medium, this remains dark, so the whole picture is completely dark. Again, such images are only slightly disturbed by a label edge.

In a further embodiment, this method is extended once more by using not only one light source with a specific wavelength, but two or more light sources each with specifically selected wavelengths. In this case, at least one light source should be strongly absorbed by one of the existing media and a different light source from the same medium should be absorbed only slightly.

In some cases, the physical interface can form a meniscus, so it can, especially at the edge of the glass wall, be strongly curved. This leads in the 2-dimensional image to a curvature of the imaged interface. The boundary to this no longer straight line of the bright spot will be curved or circular. In this way, one can also conclude on the strength of the meniscus.

To select the wavelength: When using only one light source, the wavelength should be chosen so that this light is absorbed little in at least one medium.

Dewing or slight frosting on the glass wall or on the applied label disturbs the measurement method according to the invention only slightly. Again, the essential optical properties of the light rays remain unchanged. When entering the light, they do not increase the real or apparent light source. They do not change the beam angles significantly. In the case of slight frosting, some light scattering will occur. This is very similar to the effect of light scattering in an applied white label. In the case of a dewed glass wall, there are either large areas wetted areas. These cause only a slight deflection of the rays, which makes little sense in strongly divergent rays. Or there are many small water pearls with not wetted places next to it. In the latter case, the non-wetted sites allow normal transmission of light. The water pearls lead to very strong light deflection. This works similar to very strong light scattering. The effect is therefore similar to the effect of a strongly scattering etiquette.

It will be apparent to those skilled in the art that the described embodiments are to be understood as exemplary. The invention is not limited to these but can be varied in many ways without departing from the spirit of the invention. Features of individual embodiments and the features mentioned in the general part of the description can each be combined with each other and with each other.

LIST OF REFERENCE NUMBERS

1

Container or sample tube or glass tube

1a

Entry side or entrance surface for the transmitted light into the container

1b

Exit side or exit surface for the transmitted light from the container

1c

Side wall of the container

1d

Longitudinal axis of the container

2

First medium or water

3

Interface or interface between two media

4

Second medium or oil

5

Interface or interface between two media

6

air

7

Interface or interface between two media

10

Etiquette or paper etiquette

20

Light source or transmitter or LED or LED array or LED line

21

Focusing optical component or lens

22

Source area or source point or focus

23

Transmitted light or transmitted beam or light beam

24

Opening angle of transmitted light

Claims (22)

Arrangement for detecting at least one level of a medium ( 2 . 4 ), preferably a fluid, in a container ( 1 ) full An area for receiving a container ( 1 ) with at least one in an interior of the container ( 1 ) introduced medium ( 2 . 4 ), - a transmitting unit for providing a transmitted light ( 23 ), which on one side of the receptacle for the container ( 1 ), - a receiving unit for the transmitted light ( 23 ), which on one of the transmitting unit opposite side of the receiving area for the container ( 1 ) is arranged, - wherein the transmitting unit is arranged to the receiving area such that a positioned in the receiving area container ( 1 ) substantially transversely, preferably perpendicular, to its longitudinal axis ( 1d ) by means of the transmitted light ( 23 ) is transilluminable, wherein the transmitting unit has a source area ( 22 ) for the transmitted light ( 23 ) at the receiving area for the container ( 1 ), so that the transmitted light ( 23 ) starting from the source area ( 23 ) with a divergent course of radiation into the container ( 1 ) entry. Arrangement according to the preceding claim, characterized in that the transmitting unit is a light source ( 20 ) that covers the source area ( 22 ) for the transmitted light ( 23 ) and on one side ( 1a ) of the container ( 1 ) is arranged at which the transmitted light ( 23 ) in the container ( 1 ) entry. Arrangement according to at least one of the preceding claims, characterized in that the light source ( 20 ) at a distance of less than about 8 mm, preferably less than about 3 mm, to a side ( 1a ) of the container ( 1a ) at which the transmitted light ( 23 ) in the container ( 1 ) occurs, is arranged. Arrangement according to at least one of the preceding claims, characterized in that the transmitting unit is a light source ( 20 ) and an optical component ( 21 ), wherein the transmitted light ( 23 ) by means of the optical component ( 21 ) on one side ( 1a ) of the container ( 1 ) focusable at which the transmitted light ( 23 ) in the container ( 1 ), the source area ( 22 ) for the transmitted light ( 22 ) through the focus ( 22 ) of the optical component ( 21 ) is defined. Arrangement according to at least one of the preceding claims, characterized in that the focus ( 22 ) at a distance of less than about 8 mm, preferably less than about 3 mm, outside or inside the side ( 1a ) of the container ( 1 ) at which the transmitted light ( 23 ) in the container ( 1 ) is provided. Arrangement according to at least one of the preceding claims, characterized in that the transmitted light ( 23 ) in focus ( 22 ) has a transmission spot with a diameter of less than 6 mm, preferably 3 mm, or a light gap with a width of less than 6 mm, preferably 3 mm. Arrangement according to at least one of the preceding claims, characterized in that the receiving unit comprises a receiver which on one side ( 1b ) of the container ( 1 ) at which the transmitted light ( 23 ) from the container ( 1 ) exit is arranged. Arrangement according to at least one of the preceding claims, characterized in that the receiving unit comprises a receiver and an optical component, wherein the receiver is spaced apart from one side ( 1b ) of the container ( 1 ) at which the transmitted light ( 23 ) from the container ( 1 ), is arranged and the from the container ( 1 ) emitted light can be imaged by means of the optical component on the receiver. Arrangement according to at least one of the preceding claims, characterized in that the receiver comprises at least one 1-dimensional or 2-dimensional image sensor and / or at least one brightness sensor. Arrangement according to at least one of the preceding claims, characterized in that the optical component for imaging the out of the container ( 1 ) emitted by at least one lens, a lens and / or a lens array, preferably a CIS lens array (contact image sensor) comprises. Arrangement according to at least one of the preceding claims, characterized in that the transmitting unit and the container ( 1 ), and in particular the receiving unit, or the transmitting unit together with the receiving unit and the container ( 1 ) are movable relative to each other, in particular along the longitudinal axis ( 1d ) and / or over the circumference of the container ( 1 ), so that the container ( 1 ) along its longitudinal axis ( 1d ) and / or scanned over its circumference. Arrangement according to at least one of the preceding claims, characterized in that the light source ( 20 ) by a plurality of individual light sources ( 20 ), which along the longitudinal axis ( 1d ) of the container ( 1 ) and / or over the circumference of the container ( 1 ) are arranged distributed. Arrangement according to at least one of the preceding claims, characterized by a device for driving the individual light sources ( 20 ), so that they can be switched on and / or off in chronological succession and used to scan the container ( 1 ) a preferably pulsed transmitted light along the longitudinal axis ( 1d ) and / or over the circumference of the container ( 1 ) is available. Arrangement according to at least one of the preceding claims, characterized in that the light source ( 20 ) a transmitted light ( 23 ) emitted at a single wavelength, which is selected so that the transmitted light ( 23 ) in at least one medium ( 2 . 4 ) is little absorbed and in at least one other medium ( 2 . 4 ) is strongly absorbed and / or that the light source ( 20 ) a transmitted light ( 23 ) having at least two wavelengths chosen such that the transmitted light ( 23 ) of a first wavelength in at least one medium ( 2 . 4 ) is little absorbed and the transmitted light ( 23 ) of a second wavelength in the same medium ( 2 . 4 ) is strongly absorbed and / or that the light source ( 20 ) a transmitted light ( 23 ) is emitted in a spectral range which is selected so that the transmitted light ( 23 ) in all or in all but one medium ( 2 . 4 ) is little absorbed. Method for detecting at least one level of a medium ( 2 . 4 ) in a container ( 1 ) by placing the container ( 1 ) with a transmitted light ( 23 ) substantially transversely, preferably perpendicular, to a longitudinal axis ( 1d ) of the container ( 1 ), whereby the transmitted light ( 23 ) inside the container ( 1 ) at least in sections, starting from an entry side ( 1a ) in the container ( 1 ) in the direction of an exit side ( 1b ) from the container ( 1 ) has substantially divergent beam characteristics. Method according to the preceding claim, characterized in that the transmitted light ( 23 ) by a light source ( 20 ) at the entrance ( 1a ) of the container ( 1 ) is provided, and in particular the light source ( 20 ) at a distance of less than about 8 mm, preferably less than about 3 mm, to the entry side ( 1a ) of the container ( 1 ) is arranged. Method according to at least one of the preceding claims, characterized in that the transmitted light ( 23 ) by a light source ( 20 ), which are at a distance from the entrance side ( 1a ) and provided on the entrance side ( 1a ) of the container ( 1 ) by means of an optical component ( 21 ), in particular the focus ( 22 ) at a distance of less than about 8 mm, preferably less than about 3 mm, outside or inside the entrance side ( 1a ) of the container ( 1 ) provided. Method according to at least one of the preceding claims, characterized in that the transmitted light ( 23 ) is provided with a cone of rays, which an opening angle ( 24 ) of greater than 15 °. Method according to at least one of the preceding claims, characterized in that the transmitted light ( 23 ) in focus ( 22 ) has a transmission spot with a diameter of less than 6 mm, preferably 3 mm, or a light gap with a width of less than 6 mm, preferably 3 mm. Method according to at least one of the preceding claims, characterized in that the out of the container ( 1 ) emitted transmission light ( 23 ) is detected by a receiving unit, wherein preferably a brightness profile transversely to a Medientrennfläche ( 3 . 5 . 7 ) is detected and / or evaluated. Method according to at least one of the preceding claims, characterized in that for scanning the container ( 1 ) the light source ( 20 ) and the container ( 1 ), and in particular the receiving unit, are moved relative to each other. Method according to at least one of the preceding claims, characterized in that the transmitted light ( 23 ) by a plurality of individual light sources ( 20 ) provided along the longitudinal axis ( 1d ) and / or over the circumference of the container ( 1 ), whereby the individual light sources ( 20 ) for scanning the container ( 1 ) are switched on and / or off in a timed manner.

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