Method for determining a lower boundary surface and/or an upper boundary surface of a liquid located in a container

Abstract

The invention relates to a method for determining a lower boundary surface and/or an upper boundary surface of a liquid in a container, in which illumination light is emitted that is focused by an objective lens at a focal point, wherein a measurement signal reflected at the focal point is detected by a two-dimensional detection device arranged in an image plane of the objective lens, and wherein the lower boundary surface and/or the upper boundary surface is detected based on the detected measurement signal.

Claims

1.-27. (canceled)

28. A method for determining a lower boundary surface and/or an upper boundary surface of a liquid located in a container, in which illumination light is emitted, which is focused by an objective lens at a focal point, wherein a measurement signal reflected at the focal point (5) is detected by a two-dimensional detection device arranged in an image plane of the objective lens, and wherein based on the detected measurement signal, the lower boundary surface and/or the upper boundary surface is detected.

29. The method according to claim 28, wherein the focal point is moved along an optical axis of the objective lens.

30. The method according to claim 28, wherein a. based on the measurement signal, an image is generated, and/or wherein b. based on the measurement signals, multiple images are generated, wherein the measurement signals originate from focal points that are offset relative to one another in the direction of the optical axis of the objective lens and/or wherein c. at least one measurement signal is evaluated and, based on the evaluation result, the lower boundary surface and/or the upper boundary surface is detected, and/or wherein d. at least one image is evaluated and, based on the evaluation result, the lower boundary surface and/or the upper boundary surface is determined.

31. The method according to claim 30, wherein a. as part of the evaluation, it is checked whether an optical property of the measurement signal meets a threshold value condition, and/or wherein b. as part of the evaluation, it is checked whether a measurement signal intensity is greater than a threshold value, and/or wherein c. as part of the evaluation, it is checked whether a measurement signal area imaged on the detection device is larger than a predetermined threshold value area and/or wherein d. as part of the evaluation, at least one signal pattern is evaluated, and/or wherein e. as part of the evaluation, at least one signal pattern for the at least one measurement signal is evaluated, for which the threshold value condition is met.

32. The method according to claim 31, wherein it is checked whether the at least one signal pattern has at least one pattern property, including pattern size and/or pattern intensity and/or pattern contour and/or pattern position.

33. The method according to claim 32, wherein a. a measured value is determined on the basis of the signal pattern, which has the at least one pattern property, and/or wherein b. the signal pattern, which has the at least one pattern property, is evaluated as to whether it lies in a predetermined range, and a measured value is determined on the basis of the signal pattern lying in the predetermined range and/or wherein c. it is checked whether the measured value fulfils a measured value condition and/or wherein d. it is determined that the focal point is on the lower boundary surface and/or the upper boundary surface when the measured value meets the measured value condition.

34. The method according to claim 28, wherein a. the container is moved in a direction transverse or perpendicular to the optical axis of the objective lens when no measurement signal is detected and/or wherein b. a determination device for determining the lower boundary surface and/or the upper boundary surface of the liquid is moved in a direction transverse or perpendicular to the optical axis of the objective lens when no measurement signal is detected.

35. The method according to claim 28, wherein a further illumination source is provided, which illuminates the container over an area, wherein the detection device detects a further measurement signal emanating from the illuminated container.

36. The method according to claim 35, wherein a. the container is moved when an evaluation of the further measurement signal shows that only a container edge section is received, and/or wherein b. a determination device for determining the lower boundary surface and/or the upper boundary surface of the liquid is moved when an evaluation of the further measurement signal shows that only a container edge section is received.

37. The method according to claim 28, wherein a. the container and/or a determination device for determining the lower boundary surface and/or the upper boundary surface of the liquid are moved in such a way that a central axis of the container is coaxial to an optical axis of the objective lens and/or wherein b. the container and/or a determination device for determining the lower boundary surface and/or the upper boundary surface of the liquid are moved in such a way that the container edge is received.

38. A determination device for carrying out a method according to claim 28, for determining a lower boundary surface and/or an upper boundary surface of a liquid located in the container, the determination device comprising: an illumination source for emitting illumination light, an objective lens for focusing the illumination light at a focal point, a two-dimensional detection device which is arranged in an image plane of the objective lens and detects a measurement signal reflected at the focal point, and an evaluation device which, based on the measurement signal, determines the lower boundary surface and/or the upper boundary surface of the liquid in the container.

39. The determination device according to claim 38, wherein the determination device has an imaging device for imaging the at least one measurement signal.

40. The determination device according to claim 38, wherein a. the evaluation device evaluates at least one measurement signal and, based on the evaluation result, determines the lower boundary surface and/or the upper boundary surface of the liquid in the container, and/or wherein b. the evaluation device evaluates at least one image and, based on the evaluation result, determines the lower boundary surface and/or the upper boundary surface of the liquid in the container, and/or wherein c. the evaluation device checks, in the generated image, whether an optical property of the measurement signal meets a threshold condition, and/or wherein d. the evaluation device checks, in the generated image, whether at least one signal pattern has at least one pattern property, including pattern size and/or pattern contour and/or pattern position.

41. The determination device according to claim 40, wherein a. the evaluation device determines a measured value on the basis of the signal pattern, which has the at least one pattern property, and/or wherein b. the evaluation device determines a plurality of measured values on the basis of the signal pattern that have the at least one pattern property, and a value is determined on the basis of the measured values, and/or wherein c. the evaluation device evaluates the signal pattern, which has the at least one pattern property, as to whether it lies in a predetermined range, and a measured value is determined on the basis of the signal pattern lying in the predetermined range, and/or wherein d. it is checked whether the measured value and/or the determined value fulfils a value condition, and/or wherein e. it is determined that the focal point is on the lower boundary surface and/or the upper boundary surface when the measured value and/or the determined value meets the value condition.

42. A dispensing device with a dispenser for dispensing liquid into a container and a determination device according to claim 38.

43. The dispensing device according to claim 42, wherein the dispensing device has a holding device for receiving at least one container.

44. The dispensing device according to claim 43, wherein the dispensing device a. has a control device that causes the determination device and the holding device to move relative to one another, and/or b. has a control device that causes the determination device to move relative to the holding device and/or causes the holding device to move relative to the determination device and/or wherein c. the movement of the holding device and/or the determination device is directed along an optical axis of the objective lens.

45. The dispensing device according to claim 44, wherein the control device causes a. the container to be moved in a direction transverse or perpendicular to the optical axis of the objective lens when no measurement signal is detected, and/or wherein b. the determination device to be moved in a direction transverse or perpendicular to the optical axis of the objective lens when no measurement signal is detected and/or wherein c. the dispensing device has a further illumination source for illuminating the container over a wide area, and/or wherein d. the dispensing device has a further illumination source for illuminating the container, over a wide area, and the detection device detects a further measurement signal emanating from the illuminated container.

46. The dispensing device according to claim 44, wherein the control device causes a. the container to be moved when the evaluation of the further measurement signal by the evaluation device shows that only one container edge section has been received, and/or b. a determination device for determining the lower boundary surface and/or upper boundary surface of the liquid to be moved when the evaluation of the further measurement signal by the evaluation device shows that only one container edge section is detected.

47. The dispensing device according to claim 44, wherein the control device causes a. the container and/or a determination device for determining the lower boundary surface and/or upper boundary surface of the liquid to be moved in such a way that a central axis of the container is coaxial to an optical axis of the objective lens, and/or b. the container and/or a determination device for determining the lower boundary surface and/or the upper boundary surface of the liquid to be moved in such a way that the container edge is received.

Description

[0051] The subject matter of the invention is shown schematically in the figures, wherein elements that are the same or have the same effect are mostly provided with the same reference symbols. In the figures:

[0052] FIG. 1 shows a representation of a determination device and a container,

[0053] FIG. 2 shows a representation of signal patterns imaged in the detector device,

[0054] FIG. 3 shows a flow chart for determining the fill level in the container,

[0055] FIG. 4 shows a plurality of measured values depending on the position of the focal point,

[0056] FIG. 5 shows a representation of the determination device shown in FIG. 1, in which the illumination source emits illumination light,

[0057] FIG. 6 shows a representation of the determination device shown in FIG. 1, in which the further illumination source emits illumination light,

[0058] FIG. 7 shows a representation of a dispensing device with the determination device.

[0059] The determination device 11 shown in FIG. 1 is used to determine an upper boundary surface 27, in particular a liquid surface, and/or a lower boundary surface 29, in particular a liquid bottom, of a liquid 2 in a container 1. The container 1 is filled with a liquid 2. The liquid fill level F corresponds to the distance between the lower boundary surface 29 and the upper boundary surface 27 along a central axis M of the container 1.

[0060] The determination device 11 has an illumination source 12 for emitting illumination light 3. In addition, the determination device 11 has an objective lens 4 for focusing the illumination light 3 at a focal point 5 that is located inside the container 1. This means that the determination device 11, in particular the objective lens 4, and the container 1 are arranged in relation to one another in such a way that the focal point 5 is located in the container 1. In the arrangement shown in FIG. 1, the central axis M of the container 1 and an optical axis 9 of the objective lens 4 are arranged coaxially to one another.

[0061] The determination device 11 also has a two-dimensional detection device 7. The two-dimensional detection device 7 can be a CCD detector. In addition, the two-dimensional detection device 7 is arranged in an image plane 8 of the objective lens 4 and detects a measurement signal 6 reflected at the focal point 5. In the figures, the illumination light 3 is shown with solid lines and the measurement signal 6 is shown with dashed lines.

[0062] In addition, the determination device 11 has an imaging device 19 and an evaluation device 20. Based on the detected measurement signal 6, the evaluation device 20 determines the liquid fill level of the liquid 2 in the container 1. The imaging device 19 is electrically connected to the detection device 7. In particular, the imaging device 19 generates an image on the basis of the detected measurement signal 6. The evaluation device 20 is electrically connected to the imaging device 19 and evaluates the image and/or the detected measurement signal 6. The evaluation result of the evaluation device 20 can be transmitted to a control device 18 of a dispensing device 14 shown in FIG. 6.

[0063] The illumination source 12 can be a fibre or laser diode, or other suitable illumination source. In particular, the illumination source 12 can emit illumination light of a predetermined wavelength. The emitted illumination light 3 is brought to a suitable angle of divergence by a lens 16. The illumination light 3 is forwarded to a beam splitter 23. The beam splitter can be a dichroic beam splitter. The light deflected by the beam splitter 23 passes through the objective lens 4 and is focused at the focal point 5. The beam splitter 23 is designed in such a way that it deflects at least part of the illumination light 3, in particular all of the illumination light 3, in the direction of the objective lens 4. In addition, at least part of the measurement signal 6 passes through the beam splitter 23.

[0064] The measurement signal 6 reflected from the focal point 5 is focused by the objective lens 4 at the point 24 of the image plane 8. The measurement signal 6 passes through the beam splitter 23 and is detected by the detection device 7 arranged in the image plane 8. Since the detection device 7 is a two-dimensional detection device 7, the fill level can be detected even when the upper boundary surface 27 is in motion due to a displacement of the container 1 and/or vibrations. This causes the point 24 in the image plane 8 to be shifted perpendicular to the optical axis 9. Due to the two-dimensional design of the detection device 7, the shifted point 24 can also be detected.

[0065] FIG. 2 shows an exemplary representation of the measurement signal 6 imaged in the image plane 8. The measurement signal 6 is detected by the detector device 7 and has a plurality of signal patterns, namely a first signal pattern 25a, a second signal pattern 25b, a third signal pattern 25c, a fourth signal pattern 25d and a fifth signal pattern 25e. The individual signal patterns 25a-25e differ from one another in their pattern properties. In particular, they differ from one another in pattern size, pattern position and pattern contour.

[0066] A predetermined area 30 is also drawn in in FIG. 2 in the area of the third signal pattern 25c. Part of the third signal pattern 25c lies in the specified area 30.

[0067] FIG. 3 shows a flow chart for determining the upper boundary surface 27 of the liquid 2 in the container 1. In a first step S1, the illumination source 12 is switched on, so that the container 1, in particular the focal point 5, is exposed to illumination light 3. In particular, the illumination light 3 emitted, in particular the entirety of it, emitted by the illumination source 12 is focused at the focal point 5 and the measurement signal 6 reflected from the focal point 5, which is a reflected measurement light, is detected in the detection device 7. The imaging device 19 generates an image based on the detected measurement signal 6.

[0068] Subsequently, the determination device 11 is moved along the optical axis 9 so that the focal point 5 is offset along the optical axis 9. A new image is generated with each method step. As a result, a large number of detected measurement signals 6 are obtained and/or a large number of images are generated that show the focal point 5 at different positions along the optical axis 8. FIG. 1 shows the position of the determination device 11 in which the focal point 5 is on the upper boundary surface 27.

[0069] The evaluation device 20 evaluates the images and/or the detected measurement signal 6 in a second step S2. The evaluation of the measurement signal 6 in the second step has a number of sub-steps.

[0070] In a first sub-step S21, the measurement signal intensity is determined. In a second sub-step S22, it is checked whether the measurement signal intensity exceeds a predetermined threshold value. If this is not the case, in a third sub-step S23 the generated image is discarded and/or the measurement signal 6 is not processed further.

[0071] If the measured signal intensity determined is above the predetermined threshold value, a fourth sub-step S24 checks whether the signal patterns 25a-25d shown in FIG. 2 have at least one pattern property. The check can be carried out for each image or measurement signal. In particular, in this case all signal patterns are evaluated, as described below, and a decision is then made as to which of the signal patterns is relevant for determining the upper boundary surface 27, in particular the phase boundary between the liquid and the air.

[0072] Thus, in the fourth sub-step S24, it is checked whether the respective signal pattern has a predetermined pattern contour and/or a specific pattern position and/or a pattern size. As a result, for example, signal patterns that are not round or essentially round in shape and/or are larger than a predetermined size can be filtered out. In addition, signal patterns that are located at the edges of the image and are therefore not centrally located are discarded. When these principles are applied, it is determined with the signal patterns shown in FIG. 2 that the third signal pattern 25c is the relevant signal pattern. For this signal pattern, the signal is added that is located in a central predetermined area 30 with a predetermined size. The predetermined area 30 can be dependent on the detection device 7 and is shown by way of example as a circular area of the third signal pattern 25c. This added signal results in a measured value M1-M6.

[0073] In a third step S3, the position of the determination device 11 is stored in an electrical memory, to which the signal added in the signal pattern 25c, the measured value M1-M6, is also stored in the electrical memory. This procedure is repeated for a plurality, but at least one, position of the determination device. The position of the determination device 11 at which the focal point 5 is located on the liquid surface 27 can be determined from the stored data.

[0074] This is explained using FIG. 4. FIG. 4 shows the course of a plurality of measured values M1-M6 over the position of the focal point 5 and/or the position of the determination device 11. FIG. 4 shows the progression of measured values that result in the vicinity of the upper boundary surface 27.

[0075] It is checked whether a value condition is met. In particular, it is checked whether the individual measured values M1-M6 are below or above a predetermined measured value 31, in particular a value line. The measured values M1-M3 and M5 and M6 are below the specified value 31, in particular a value line, and are not considered relevant.

[0076] The focal point 5 lies on the upper boundary surface 27 when the measured value exceeds the determined, previously specified (instrument-dependent) measured value 31 and/or when the measured value reaches a local maximum, i.e. the measured values of the positions above and below the focal point 5 have a significantly lower value. The check utilises the fact that the reflecting surface, in particular the upper boundary surface 27, has been reached with sufficient accuracy when the measured value exceeds the predetermined measured value 31. This requirement is met with the measured value M4.

[0077] Alternatively or additionally, the data from a plurality of measured values M1-M6 can be interpolated and a curve 32 can be generated. A value B1 can then be determined on the basis of the measured values M1-M6. The value B1 corresponds to a maximum of the curve 32. The maximum of the curve 32 or the determined value B1 is then at the position of the determination device 11 that corresponds to the upper boundary surface 27.

[0078] In a dispensing process by the dispensing device 14 shown in FIG. 7, the determination device 11 can thus determine precisely the partial area of the container 1 to be scanned if it knows the fill level, in particular the upper boundary surface 27. As already described above, a partial area is scanned in order to determine whether the dispensed droplet has landed in the container.

[0079] FIG. 3 describes a sequence of how an upper boundary surface 27 of the liquid 2 is determined. The lower boundary surface 29 can be determined in the same way as the upper boundary surface 27.

[0080] FIG. 5 shows a representation of the determination device 11 shown in FIG. 1, in which the illumination source 12 emits illumination light. In contrast to FIG. 1, the container 1 and the receiving device 11 are arranged relative to one another in such a way that the central axis M of the container 1 and an optical axis 9 of the objective lens 4 are not coaxial to one another. This means that the focal point 5 is not on the central axis M of the container. The focal point 5 is in a meniscus area 26 of the liquid 2. As can be seen from FIG. 5, the measurement signal 6 reflected by the focal point 5 does not reach the objective lens 4 and therefore cannot be detected by the detection device 7.

[0081] FIG. 6 shows an illustration of the determination device shown in FIG. 1, in which a further illumination source 21 (not shown in FIG. 1) emits illumination light. The additional illumination source 21 is used to to illuminate the area of the container 1. The detection device 7 receives a further measurement signal 13 emanating from the container 1. In the present case, no illumination light is emitted by the illumination source 12. The illumination source 12 and the additional illumination source 21 are arranged on opposite sides of the container 1.

[0082] The evaluation device 20 evaluates the further measurement signal 13 to determine whether a container edge, in particular the entire container edge, is detected. In the arrangement shown in FIG. 6, it is determined that only part of the edge of the container is detected. The evaluation device 20 transmits the evaluation result to the control device 18. This causes the determination device 11 and/or the container 1 to be moved in such a way that the central axis M of the container 1 is coaxial to the optical axis 9. In this case, the state shown in FIG. 1 is present and the detection device 7 detects the entire edge of the container.

[0083] FIG. 7 shows a representation of a dispensing device 14 with the determination device 11. The additional illumination source 21 is not represented in FIG. 7. The dispensing device 13 has a dispenser 15 for dispensing a liquid 2. The liquid dispensed may contain no biological particles or may contain at least one particle. The dispenser 15 can be a droplet generator that, as shown in FIG. 7, dispenses liquid in the form of a droplet.

[0084] FIG. 7 shows a state in which the dispenser 15 has dispensed a droplet. The droplet is fed into a container 1. FIG. 7 shows two containers 1 that are held by a holding device 17 of the dispensing device 14. The dispenser 15 is actuated to dispense the droplet by an actuator (not shown), in particular a piezo actuator.

[0085] The evaluation device 20 is electrically connected to the control device 18. The control device 18 is electrically connected to a displacement device 10. The displacement device 10 can move the dispenser 15 and/or the holding device 17 in such a way that the droplet can be dispensed into the desired storage location. In addition, the displacement device 10 can move the holding device 17 and/or the determination device 11 in order to determine the fill level F in the container 1, as described above.

[0086] In addition, the control device 18 can control a deflection and/or interception device 28 of the dispensing device 1. In this case, the control device 18 can control the deflection and/or interception device 28 in such a way that the dispensed droplet is deflected and/or intercepted before it reaches a container if, for example, a particle condition is not met.

LIST OF REFERENCE SIGNS

[0087] 1 Container [0088] 2 Liquid [0089] 3 Illumination light [0090] 4 Objective lens [0091] 5 Focal point [0092] 6 Measurement signal [0093] 7 Detection device [0094] 8 Image plane [0095] 9 Optical axis [0096] 10 Displacement device [0097] 11 Determination device [0098] 12 Illumination source [0099] 13 Further measurement signal [0100] 14 Dispensing device [0101] 15 Dispenser [0102] 16 Lens [0103] 17 Holding device [0104] 18 Control device [0105] 19 Imaging device [0106] 20 Evaluation device [0107] 21 Further illumination source [0108] 23 Beam splitter [0109] 24 Point in the image plane [0110] 25a First signal pattern [0111] 25b Second signal pattern [0112] 25c Third signal pattern [0113] 25d Fourth signal pattern [0114] 25e Fifth signal pattern [0115] 26 Meniscus area [0116] 27 Upper boundary surface [0117] 28 Deflection and/or interception device [0118] 29 Lower boundary surface [0119] 30 Predetermined area [0120] 31 Predetermined measured value [0121] 32 Curve [0122] M Central axis of the container [0123] F Liquid fill level [0124] M1-M6 Measured values [0125] B1 Determined value