SYSTEM FOR DETECTING PARTICLES IN A DAIRY FLUID SUCH

AS MILK

FIELD OF THE INVENTION

This invention relates to systems and methods for analyzing dairy fluids such as milk.

BACKGROUND OF THE INVENTION Milk typically contains, dirt specks, somatic cell aggregates, and blood clots.

Generally, the particle sizes of the particulate matter are in the range of 5 to 2,000 microns, and more particularly, 20 to 500 microns, and still more particularly, in the range of 20 to 300 microns, with a typical size being approximately 50 to 200 microns. In most countries, milk standards have been established that specify limits on the size, shape, appearance and amount of particles that may be present in milk suitable for human consumption.

US Patent 6,315,955 to Klein discloses a method and an apparatus for the quantification of particles in a fluid, including milk. During analysis of a fluid sample, data from a plurality of signal paths between one or more light emitters and one or more detectors are gathered. This information is evaluated by comparison with known data for different fluid particle contents, in order to detect particles in the fluid.

US Patent No. 6,038,030 to van den Berg discloses an apparatus for detecting the presence of contaminants in milk. A color sensing measuring system is used to determine the intensity of frequency of selected colors (red, yellow and blue) in a milk sample. The intensity values are compared with previous recorded intensities in order to determine whether or not the milk is contaminated.

SUMMARY OF THE INVENTION

The present invention is a method and system for detecting particles in a dairy fluid, such as milk, and for characterizing the particles.

The system includes a view cell having at least a pair of opposite transparent surfaces that is filled with the dairy fluid. Optical images of the dairy fluid in the view cell obtained by an optical arrangement such as a microscope are converted into digital images by a digital camera. A processor is configured to analyze images from the digital camera to detect the presence of particles in the dairy fluid sample in the view cell, and to determine one or more values of parameters relating to characteristics of any particles present in the sample. The particles may be, for example, blood clots or somatic cell aggregates. Such parameters include, for example, particle size, particle shape, particle density and particle color. This analysis may be accomplished by any commercially available software product such as the Image-Pro Plus brand of analysis software by Media Cybernetics, Inc. of Silver Spring, Md. The processor may further be configured to perform a statistical analysis of the parameter values particles obtained on a plurality of fluid samples. For example, a statistical analysis may be performed on the particle parameters of the milk of a given animal over a period of time, or on an entire herd in a single milking session.

The system of the invention is typically installed at a milking installation having a plurality of milking apparatus for milking one or more animals. The view cell may be in the milking line or may be part of a shunt path in which dairy fluid flowing in a conduit of a milking apparatus is diverted into the shunt path and conducted to the view cell. The processor may be configured, when unacceptable amounts or types of particles are detected in the sample, to adjust a valve hi order to divert the flow of milk to a bulk milk tank to an auxiliary receptacle. In this way, milk which does not meet one or more predetermined standards, for example, standards for milk suitable for human consumption, can be collected separately and either discarded or used for other purposes. When substandard milk is detected, the processor may generate a sensible signal such as activating an alarm. The invention thus provides a system for detecting particles in a dairy fluid, comprising:

(a) a view cell;

(b) a digital camera producing digital images of the dairy fluid in the view cell; and

(c) a processor configured to detect particles in a digital image obtained by the camera.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 shows a system for detecting particles in a dairy fluid system in accordance with one embodiment of the invention; and

Fig. 2 shows the optical arrangement of the system of Fig. 1.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Fig. 1 shows a system, generally indicated by 1, for detecting particles in a dairy fluid such as milk, in accordance with one embodiment of the present invention. For the sake of clarity, the dairy fluid is referred to herein as "milk", it being understood that the system 1 may be used for detecting particles in other dairy fluids such as cream. The system 1 is preferably installed at a milking installation, as shown in Fig. 1. The milking installation includes one or more milking apparatus for milking one or more animals. (A single milking apparatus is shown schematically in Fig. 1 for simplicity only) Each milking apparatus includes a cluster 3 of four teat cups 2 configured to be connected to the teats of an animal to be milked. Milk received in the teat cups 2 is conducted via milk discharge tubes 4 and conduit 6 to a milk glass 8. The milk glass 8 is also connected to a vacuum line 10 for generating a vacuum in the milk conduction system consisting of the teat cups 2, the milk discharge tubes 4, milk conduit 6 and milk glass 8, in order to retain the teat cups 2 on the teats of the animal being milked, and for conducting milk from the teat cups 2 to the milk glass 8 where the milk is separated from air present in the milk. The milk received in the milk glass 8 is subsequently conducted through an exit conduit 12 to a bulk milk tank 14 under the influence of a pump 16. The exit conduit 12 is provided with a valve 18, a non-return valve 20 and a three-way valve 22.

The milk analysis system 1 of the invention includes a view cell 24 having a transparent bottom surface 25 and a transparent upper surface 27 parallel to the bottom surface 25. The viewing cell is incorporated into the milk conduit 6 so that milk flowing in the conduit 6 between the cluster 3 and the milk glass 8 flows through the view cell 24. The view cell 24 has a cross-sectional area about equal to that of the milk conduit 6 in order not to retard the flow of milk in the milk conduit 6, or to generate a higher fluid pressure in the view cell 24. The system 1 further includes an optical system 28 for viewing the milk sample 26 in the view cell 24. Optical images of the milk sample 26 are created by the optical system 28 as explained below and converted into an electronic data signal by a digital camera 42. The electronic signals indicative of optical images obtained by the microscope 28 are transmitted to a CPU 44 over a transmission line 46. The CPU 44 may be a personal computer of a type known in the art having a processing unit 47, memory 48, optional internal magnetic and/or optical storage devices, and interface circuitry to communicate with digital camera 42. The processor 47 is configured to analyze images obtained by the camera 42 for the presence, size, shape, and appearance of particles, as explained below. The images and the results of the analysis may be stored in the memory 48. The images and the results of the analysis may be displayed on a monitor 50. A data input device, such as a keypad 52 allows an operator to input data or instructions to the CPU 44. The transmission line 46 may be a wired connection or a wireless connection. The CPU and monitor may be located adjacent to the optical system 28, or may be remotely located.

The optical system 28 is designed according to the size of the particles to be detected. Fig. 2 shows the optical system 28 designed as a compound optical system. In this case the optical system 28 includes light source 30, a light filter 32, a condenser 34, a diaphragm 36, one or more objective lenses 38, and one or more ocular lenses 40. Light from the light source 30 passes though the light filter 32 and is focused by the condenser 34 through the bottom surface of the view cell 24 onto the focal plane of the objective lens 38 located inside the view cell 24. Light transmitted through the view cell 24 and the milk sample 26 is collected by the objective lens 38 through the upper surface of the view cell 24 focused on the focal plane of the ocular lens 40. The ocular lens 40 focuses the light on a focal plane of the digital camera which is typically the plane of a charge coupled device (CCD) in the camera 42. In the system shown in Fig. 2, images are formed by light transmitted through the milk sample in the view cell 24.

This is by way of example only, and other optical arrangements may be used to form optical images of the milk sample 26, such as reflected light, phase contrast, and the like may also be used in the system of the invention.

The camera 42 may be a digital still camera. In this case, an image may be obtained by the camera 42 when a command to obtain an image is input by the operator using the keypad 52. Alternatively, the processor 47 may be configured to obtain an image from the camera 42 at a selectable rate, for example one picture every minute, in order to monitor the milk in the view cell 24 as milk flows through the view cell 24. Alternatively, the camera 42 may be a video camera or the like, which automatically obtains images at a rate that is suitable for continuous playback and analysis.

The processor 47 is configured to analyze images from the digital camera 42 to detect the presence of particles in the milk sample 26, and to determine one or more values of parameters relating to characteristics of any particles present in the milk sample 26. The particles may be, for example, blood clots or somatic cell aggregates. Such parameters include, for example, particle size, particle shape, particle density and particle color. This analysis may be accomplished by any commercially available software product such as the Image-Pro Plus brand of analysis software by Media Cybernetics, Inc. of Silver Spring, Md. The processor may output a result for each image. The processor 47 may store in the memory 48 the values of parameters of all of the detected particles and then perform a statistical analysis of a population of detected particles. The statistical analysis may involve calculating an average or standard deviation of a parameter in the population. The analysis may involve determining the frequency distribution of the parameter in the population. The population of particles might be, for example, from the milk of a specific animal over a period of time, the milk from an entire herd of animals during a single milking, and so on. The output may be in visual, tabular, and/or graphical form. The output is stored in the memory 48 and may be displayed on the monitor 50. The processor 47 may optionally be configured to run image enhancement software prior to analysis of an image for particle detection.

Parameter values calculated for each of a sequence of milkings of a particular animal provide a record of the quality of the animal's milk. The values obtained at a subsequent milking can be compared with the average values calculated for the previous milkings. Instead of determining average parameter values for each of the parameters, it is also possible to establish a threshold value for one or more parameters. The

threshold values maybe determined from a statistical analysis of parameters values obtained during from a plurality of animals.

When unacceptable amounts or types of particles are detected in the milk sample 26, a signal is transmitted by the CPU 44 via a transmission line (not shown in Fig. 1) to the three-way valve 22 of the milking apparatus which causes the valve 22 to be adjusted so as to divert the flow of milk from the bulk milk tank 14 to an auxiliary receptacle 70 via a conduit 72. In this way, milk which does not meet one or more predetermined standards, for example, standards for milk suitable for human consumption, can be collected separately and either discarded or used for other purposes. The system 1 may include an alarm or other device producing a sensible signal that is activated by the processor 47 when milk not meeting the relevant standards is detected by the processor 47. A warning that milk not meeting relevant standards has been detected may be displayed on the monitor 50.

The light source 30 may be a broadband light source producing light in the visible range, although non- visible illumination may also be used, such as an ultraviolet light. A light filter 32 may be used to select a specific range of wavelengths from the broadband illumination, depending on the optical properties of the particle to be detected. Alternatively, a narrowband light source such as a laser or light emitting diode (LED) may be used. The size of the diaphragm 34 is selected to enhance contrast of the particles.

The optical path of the light through the view cell 24 is preferably about 1 to 3 mm in length. The depth of focus of the objective lens 38 is preferably equal to about the diameter of the largest particle to be detected in order to provide high resolution of the particles. As a result, overlap or coincidence of neighboring particles from different levels in the milk sample 26 is avoided, which might be interpreted by the particle detection software run on the processor 47 as single particle. In this way, a clearer image is obtained, and the particle size determination is more robust. Thus, for detecting particles in milk of up to about 300 microns in size, an objective lens having a focal length of approximately 20 to 300 microns is preferably used. The objective lens 38 may provide, for example, a 1OX magnification.