NZ240258A - Animal pelt or hide tester using fluorescence evoked by a light source to detect defects in the pelts or hides - Google Patents

Description

24025 Patents Form # 5 2 5/VOV /992^ NEW ZEALAND Patents A ct 1953 COMPLETE SPECIFIC ATION ^ AFTER PROVISIONAL NO : 240258 DATED : 16 December 1991 TITLE : MEASUREMENT METHOD AND APPARATUS We, Auckland UniServices Limited of UniServices House, 58 Symonds Street, Auckland, New Zealand (previously of Level 6, Engineering School, 20 Symonds Street, cX rAa fes-rf -V^-Auckland, New Zealand), and The Minister of Agrioulturc, the Minlstiy of 1 \ ^ Agtiiulture and Fisheries, 101-103 ThrTerrace, Wellington, rsew Zealand, hereby x a declare the invention, for which we pray that a patent may be granted to us, and the ^ method by which it is to be performed, to be particularly described in and by the following statement: n -1 PF05.JWP FEE CODE - 1050 240258 FIELD OF THE INVENTION The present invention relates to means or systems for testing products, particularly 5 animal products, for faults or irregularities.

OBJECT It is an object of the present invention to go at least partway towards providing a novel 10 or improved method of testing, or at least to provide the public with a useful choice.

STATEMENT OF INVENTION In one aspect the invention provides a method of testing pelts and hides for faults or 15 irregularities wherein a pelt or hide product is illuminated by a light source providing light of a wavelength or range of wavelengths capable of exciting fluorescence within the material of the product or within the material of the faults or irregularities and detecting spatial variations in fluorescence from said product.

The faults within the material may or may not involve the presence of contaminants. The products tested in this way are typically natural products such as hides.

Preferably the method includes the step of scanning the illuminated product with at least one selectively filtered optical detector.

In another aspect the present invention provides a pelt and hide testing apparatus for testing a pelt or hide product for faults or irregularities including a light source and an optical filter, wherein the light source is capable of providing light of a wavelength or range of wavelengths other than the fluorescent wavelength of the product, and the 30 optical filter is capable of allowing transmission of any fluorescent emissions from the product but blocking substantially all detectable wavelengths of the light emitted by the light source.

Preferably the light source is substantially monochromatic.

Preferably the wavelength lies in the range from 480 to 515 nanometers; i.e. in the blue-green region of the visible spectrum.

| N.Z. PATENT OFFICE j i. . i ' ■ " 11 '■ 31 MM 1995 RECEIVED 240258 Preferably the light source is an Argon laser.

Preferably the filtering used in association with the optical detector transmits orange-5 red light.

Preferably the method and/or apparatus is adapted for use in the detection of irregularities in pelts or hides.

PREFERRED EMBODIMENT The following is a description of a preferred form of the present invention, given by way of example only, with reference to the accompanying drawing in which: Figure 1 schematically illustrates the preferred apparatus and process of the present invention.

The preferred form of the present invention described in this example of the invention comprises a system 10 for detecting blemishes in pelts or hides 11. It should be 20 appreciated that the same process might be used to detect blemishes in fruit, wood, meat, or a variety of other relatively large natural products, and possibly also in some synthetic products.

Defects may occur in pelts or hides as the result of any of a number of different causes. 25 This may include scarring from injuries sustained by the animal at any previous time, viral or other infections, ulcerative and erosive lesions, seed penetration, or damage during processing of the pelt or hide. One particular defect of economic importance is termed "cockle".

It has been surprisingly found that when the cleaned surface of a hide 11 is viewed in a particular manner any blemishes and defects are emphasised, and quality control may thereby be exercised more effectively. The particular manner envisaged is to use the phenomenon of fluorescence. Fluorescence is defined as the re-radiation of an absorbed photon of light at a longer wavelength. While certain synthetic dyes and other materials 35 exhibit strong fluorescence, natural autofluorescence at low levels is a widespread phenomenon, particularly within animal tissues. It may be raised or quenched by local 5324CS4.N92 240258 variables, such as blemishes and defects in the hide 11.

A particularly successful arrangement for detecting this natural fluorescence is to use an 5 argon laser 13, which radiates in the blue-green portion of the visible spectrum, to illuminate broad areas 15 of the hide 11 under investigation, and visually examine the irradiated hide through filter glasses 17 transmitting wavelengths no shorter than orange-red to red. Thus fluorescence in the orange-red to red range, emitted by molecules illuminated with photons of blue-green light, is detected and local variations 10 in intensity prove to be strongly correlated with otherwise almost invisible defects.

The predominant wavelengths emitted by an argon laser are blue-green light, at 514.5 nm and 488 nm. The preferred filters - to selectively transmit fluorescence evoked by the blue-green light yet block the exciting wavelengths - have an orange-red appearance 15 and exhibit a high optical density of 11.5 at 514.5 nm, and 13 at 488 nm.

Preferably, the hide 11 is stretched on a frame 12, and may be carried by any suitable conveying means through a darkened area or room, in which the inspector 16 works. The conveying means preferably carries the hide past the laser or other light source at 20 right angles to the beam and at a set distance, so that all parts of the hide 11, and all subsequent hides to be inspected, are at substantially the same distance from the light source, to reduce or eliminate variations in beam intensity where possible. If the light source is to be portable, it might be fitted with a measuring rod or frame to facilitate consistent positioning relative to the hide or pelt being inspected. In the case of a laser 25 light source, a beam spreading lens 14 might also be fitted, to allow a suitably sized area of the hide to be illuminated at the requisite intensity.

In a trial, lamb and sheep skins from four locations within New Zealand were graded by laser, then tanned to wet blue, and regraded according to conventional criteria. The 30 laser scanning correctly assessed 33 of 37 (89%), 23 of 30 (77%), 21 of 28 (75%), and 26 of 32 (81%) skins, thereby predicting the outcome of the tanning process. Further experience in assessment and refinements to the equipment would no doubt enhance the usefulness of the scanning process. At this stage the laser system could indicate whether a given skin was worth tanning, i.e. had no invisible defects, while the present less 35 efficient system is to tan and then grade. 5324CS4.N92 240258 Histopathologic^ examination of skin sections to establish the fundamental cause of fluorescence in damaged pelts has so far implicated only mast cells as a single particular cause of fluorescence. Laser excitation was not used in this test.

Other sources of substantially monochromatic light may be used; for example a mercury arc lamp together with filters passing only the green light at 540 nm, or perhaps the blue and violet lines of the mercury spectrum may also or alternatively be used. However the laser source has the particular advantage that ample illumination at the desired wavelength may be produced as a beam. In the trial, inadequate illumination was found to reduce the effectiveness of this assessment.

While work to date has concentrated on the blue-green to orange-red fluorescence, it is likely that other wavelength or colour pairs may when examined provide useful information. It should be realised that informative fluorescence may well appear in the infra-red and can only be detected by means of equipment such as silicon photodiodes, perhaps in the form of a diode array, PIN photodiodes, or a solid-state or CCD television camera.

The use of instrumental detectors leads to the known advantages of the use of non-human quality control, for humans may suffer from wandering attention, drift in standards, etc whereas instruments are relatively stable over long periods of time and even on Monday mornings.

While a hide could be graded according to averaged fluorescent emission from the whole surface, it is preferable to examine it point by point because defects may be small. This approach lends itself to image analysis techniques, involving building up an array of imaged data in a computer memory, since such techniques which are becoming widely available commonly involve from 10,000 to a million data points.

A laser source to be used in conjunction with image processing methods could be made to scan a narrow, intense beam over the surface in a kind of raster scan, using revolving or other types of moving mirrors.

Staining techniques could be used in conjunction with detection means as described above, to enhance the fluorescence, but this may be less preferred in general practice, as 5324CS4.N92 240258 it may reduce the value of the pelt. Staining might be used on samples from a batch of hides to enhance detection, and possibly allow the specific cause of defects to be distinguished and eliminated from subsequent batches. The degree of fluorescence is 5 found to naturally vary in defects of different types - for example, mast cell tumours exhibit very strong fluorescence - and this may be found sufficient to allow the cause of some defects to be distinguished without staining.

It should be appreciated that the degree of accuracy with which blemishes are detected 10 may be varied to suit specific industries or tasks. In some cases it may be found acceptable to use a less expensive, less accurate alternative to apparatus as described above. It should be noted that in tests conducted on the invention to date, over 70% of faults in hides have been detected using the electronic scanner of the present invention, compared to less than 10% of faults being detected in the grading systems currently 15 used by the fellmongering industry. Many of the faults passing undetected by the system of the present invention are found to be so slight as to have no effect on the value of the tanned product It should be appreciated therefore, that a wide variety of changes and modifications 20 might be made to the above examples within the general scope of the present invention, as set forth in the following claims. 5324CS4.N92 240258

Claims (10)

1. WHAT WE CLAIM IS: •> 1. A method of testing pelts and hides for faults or irregularities wherein a pelt or hide product is illuminated by a light source providing light of a wavelength or range of wavelengths capable of exciting fluorescence within the material of said product or within the material of the faults or irregularities and detecting spatial variations in fluorescence from said product. 10
2. 2. A method as claimed in claim 1 further including the step of scanning the illuminated product with a selectively filtered beam of light of the light source.
3. 3. A method as claimed in claim 1 wherein the light source is a laser emitting light in the blue-green portion of the visible spectrum.
4. 4. A method as claimed in claim 3, wherein the laser is an argon laser.
5. 5. A method as claimed in claim 3 or 4, wherein the light from the laser is emitted through a beam spreading lens before illuminating the product.
6. 6. A method as claimed in claim 1 wherein variations in fluorescence from said product are detected by viewing the product through a filter which selectively allows transmission of the fluorescent wavelength but excludes most of the light from the light source.
7. 7. A method as claimed in claim 1 wherein the spatial variations in fluorescence from said product are detected by an instrumental detector. 30 35
8. 8. A pelt and hide testing apparatus for testing a pelt or hide product for faults or irregularities, including a light source and an optical filter, wherein the light source is capable of providing light of a wavelength or range of wavelengths other than the fluorescent wavelength of said product, and the optical filter is capable of allowing transmission of the fluorescent wavelength of said product but blocking substantially all of the light from the light emitted by the light source. Z. PATENT OFFICE 5324C54.595/gg 1 MAY 1995 1" »* I 240258 -8-
9. 9. A method of testing pelts and hides for faults or irregularities substantially as herein described with reference to the accompanying drawing.
10. 10. A pelt and hide testing apparatus substantially as herein described with reference to the accompanying drawing. 10 JAMES W. PIPER & CO. Attorneys for the Applicants: Auckland UniServices Ltd and The Minister of Agriculture 15 20 25 30 35 5324CS4.595/gg