Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination

Definitions

• the present invention relates to a measurement instrument and a method for measuring the degree of covering of dust and dirt on a surface, preferably for the purpose of monitoring cleaning quality after cleaning.
• An objective measurement method can also be used, for example, for drawing comparisons between different cleaning methods.
• a method is at present available on the market which permits such objective measurements.
• the known method uses a measurement instrument specially built for the purpose, in which a laser beam passes through a transparent test film with a certain covering of dust, the light transmission of the film being measured by means of a photodetector, on the opposite side of the test film from the laser beam source, registering the intensity of the light which has passed through the test film.
• the measurement instrument must first have been calibrated by light being passed through the test film in the dust-free state. The degree of covering of dust and dirt is then indicated as a function of the difference between the registered light intensity on passing light through the dust-free test film and the slightly lower light intensity which is registered on passing light through the dust-covered test film.
• the test film used in the known method is of the same type used, for example, by police authorities when taking finger prints.
• the film is coated with an adhesive layer which, prior to the film being used, is protected by a protective film.
• the protective film is removed and the test film is applied with a predetermined pressure against the surface whose covering of dust and dirt is to be measured, with any dust and dirt particles from the surface attaching themselves to the adhesive layer.
• the film is then placed in a holder in the measurement instrument and light is passed through it in accordance with the above.
• a disadvantage of the known measurement instrument is that, because of the advanced laser technology used, it is too expensive to be purchased by small or medium-sized cleaning companies, or by the actual party paying for the cleaning services. In addition, the weight and external dimensions of the measurement instrument are such that it is rather impractical for frequent use.
• a further disadvantage of the known measurement instrument is that, for each measurement, it has to be calibrated with respect to the individual test film, which means that the film has to be placed twice in the measurement instrument for each point of measurement in the premises which have been cleaned.
• the present invention therefore makes available a measurement instrument for measuring the degree of covering of dust and dirt on a surface, for example in order to monitor cleaning quality, comprising a holder by means of which a measurement object in the form of a test film is held, during measurement, in a plane in a measurement zone defined by the measurement instrument, the said test film being coated with an adhesive layer which, during testing of the surface, is intended to pick up any dust and dirt particles from the said surface.
• the measurement instrument according to the invention is characterized in particular by:
• a processor (14) intended to present a measurement value which represents the degree of covering of dust and dirt on the surface (30), the said measurement value being based on the light intensity registered by the photodetector (8).
• the invention also relates to a method for measuring the degree of covering of dust and dirt on a surface, for example in order to monitor cleaning quality, comprising the following stages:
• a test film coated with an adhesive layer is applied with a predetermined pressure against the surface whose degree of covering of dust and dirt is to be measured, with any dust and dirt particles from the said surface attaching themselves to the adhesive layer;
• test film is then removed from the said surface and is placed in a holder which, at least during measurement, holds the test film in a plane in a measurement zone defined by the measurement instrument,
• a light source illuminates the adhesive layer of the test film with obliquely incident light
• a photodetector registers the light intensity of the light reflected from the test film
• a processor (14) presents a measurement value which represents the degree of covering of dust and dirt on the surface (30), the said measurement value being based on the light intensity registered by the photodetector (8).
• a gloss meter of the type which measures light reflected from a surface, is used as a measurement instrument for measuring the degree of covering of dust and dirt on a surface, for example in order to monitor cleaning quality, together with a test film coated with an adhesive layer.
• Fig. 1 shows a diagrammatic view of a measurement instrument according to the prior art
• Fig. 2 shows a diagrammatic view of a measurement instrument according to the invention
• Fig. 3 shows an enlarged perspective view of a test film according to the invention
• Fig. 4 shows how the test film is pressed against the surface whose degree of covering of dust and dirt is to be measured
• Fig. 5 shows a perspective view of a measurement instrument according to a preferred embodiment of the invention, where the test film has been placed in the holder prior to measurement.
• a measurement instrument (A) according to the prior art is first shown in Fig. 1.
• the measurement instrument (A) is here accommodated in an oblong casing (B) which is provided with an opening (C) for introduction of a test film (D).
• the instrument works by means of a laser beam generated from a laser beam source (E) passing through a transparent test film (D) with a certain covering of dust, the light transmission of the film being measured by means of a photodetector (F), on the opposite side of the test film (D) from the laser beam source (E), registering the intensity of the light which has passed through the test film (D).
• the measurement instrument (A) will first have to have been calibrated by light being passed through the test film (D) in the dust-free state.
• the degree of covering of dust and dirt is then indicated as a function of the difference between the registered light intensity when light is passed through the dust-free test film (D) and the slightly lower light intensity which is registered when light is passed through the dust-covered test film (D).
• Fig. 2 shows a diagrammatic outline view of a measurement instrument 1 according to a preferred embodiment of the invention.
• the measurement instrument is designated in general by reference number 1 and is accommodated in a casing 2.
• the casing 2 is preferably made of a lightweight material such as plastic or aluminium, since the measurement instrument 1 is dimensioned such that it can be held in one hand by a user.
• the measurement instrument 1 is further provided with a holder 2 by means of which a measurement object in the form of a test film 3 is maintained in a plane in a measurement zone 4 defined by the measurement instrument 1.
• the holder 2 can be moved relative to the rest of the measurement instrument 1 , and it can be pushed between a first, open position as shown in Fig. 5 and a second, closed position as shown in Fig. 2.
• the holder 2 is further provided with securing members 10 for securing a test film 3 without tensioning.
• the securing members 10 consist of tongue elements connected to the holder 2 by means of rivets 11.
• the securing members 10 can of course be formed in another way. It is important for the test film 3 to be secured without tensioning such that it lies flat in the holder 2 without bending, which bends would otherwise have an adverse effect on the measurement result.
• the holder 2 is arranged so that it can be detached from the rest of the measurement instrument 1.
• the measurement instrument 1 can be calibrated by means of a dust-free and dirt-free test film 3 being placed in the holder 2, with measurement taking place after a calibration button 20 has been depressed. In this way, the instrument is calibrated exactly to the test film which is being used in the subsequent test and measurement, as a result of which the greatest accuracy of measurement is achieved.
• calibration does not necessarily have to take place before measurement, since a corresponding calibration measurement value related to an average test film is stored in a processor 14 in the measurement instrument 1 , with the processor 14 using this stored calibration measurement value when no calibration is carried out before the actual measurement.
• test film 3 which is shown enlarged in Fig. 3, is of the same type as is used, for example, by police authorities when taking finger prints.
• the film 3 is coated with an adhesive layer 5 which, before the film 3 is used, is protected under a protective film 13.
• Fig. 4 shows how the test film 3 is used for testing a surface 30.
• the protective film 13 is removed and the test film 3 is applied with a predetermined pressure - preferably by means of a roller 32 specially designed for the purpose and available on the market - against the surface 30 whose degree of covering with dust and dirt is to be measured. Any dust and dirt particles 31 from the surface 30 attach themselves to the adhesive layer 5.
• the test film 3 is then placed in the holder 2 of the measurement instrument 1 with the adhesive layer 5 facing upwards, as can be seen in Fig. 5, and the holder 2 is pushed in to its closed position (not shown) in the direction of arrow 18 and the measurement is carried out.
• the instrument 1 comprises a light source 6 intended to illuminate the adhesive layer 5 of the test film 3 with obliquely incident light, which test film is placed in the holder 2 during measurement in such a way that its adhesive layer 5 is directed towards the light source 6.
• An optical lens 7 is placed between the light source 6 and the measurement zone 4, which lens 7 is designed to parallelize the light beams 12 impacting the test film 3.
• a photodetector 8 is intended to register the light intensity of the light reflected from the test film 3.
• An optical lens 9 is placed between the measurement zone 4 and the photodetector 8, which lens is designed to concentrate the light beams 21 which are reflected from the test film 3 towards the photodetector 8 at an angle of reflection ⁇ .
• the measurement instrument is further provided with a processor 14 intended to compare the light intensity registered by the photodetector 8 with a predetermined calibration value, and to present a measurement value based on the said comparison, which measurement value represents the degree of covering of dust and dirt on the surface 30 (see Fig. 4).
• the measurement value is presented in a display window 22 formed in the casing 15, as can best be seen in Fig. 5.
• the degree of covering of dust and dirt is normally indicated as a percentage of the measurement value (100%) which is obtained on a clean surface, i.e. a surface free of dust and dirt.
• the method according to the invention is carried out in the following stages:
• a test film 3 coated with an adhesive layer 5 is applied with a predetermined pressure against the surface 30 whose degree of covering of dust and dirt is to be measured, with any dust and dirt particles 31 from the said surface 30 attaching themselves to the adhesive layer 5;
• test film 3 is then removed from the said surface 30 and is placed in a holder 2 which, at least during measurement, holds the test film 3 in a plane in a measurement zone 4 defined by the measurement instrument 1 ,
• a light source 6 illuminates the adhesive layer 5 of the test film 3 with obliquely incident light
• a photodetector 8 registers the light intensity of the light reflected from the test film 3; and - a processor 14 compares the light intensity registered by the photodetector 8 with a predetermined calibration value, and presents a measurement value based on the said comparison, which measurement value represents the degree of covering of dust and dirt on the surface 30.
• a portable gloss meter of a known type which measures reflected light from a surface and presents a measurement value in the form of a gloss number, can advantageously be adapted for use as a measurement instrument 1 according to the invention, by means of a holder 2 according to the above description being mounted in the measurement opening of the gloss meter.
• a measurement instrument is obtained which is much more compact and easier to handle compared to the known measurement instrument described above with reference to Fig. 1 , and it also costs much less on account of the fact that such a gloss meter is manufactured in considerably larger batches.
• the invention therefore makes available an inexpensive and effective method of measuring cleaning quality, which method can be used to great advantage by cleaning companies for their own monitoring purposes, or by cleaning contractors such as schools, nurseries and hospitals.
• the holder 2 can be designed as a pivotable cover or can be integrated in a protective plate which normally accompanies the gloss meter of the above-described type for the purpose of protecting the measurement opening when the instrument is not in use.

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• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
• Sampling And Sample Adjustment (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

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• 1998
  • 1998-12-17 SE SE9804398A patent/SE521948C2/sv not_active IP Right Cessation
• 1999
  • 1999-12-17 WO PCT/SE1999/002405 patent/WO2000039566A1/en not_active Application Discontinuation
  • 1999-12-17 EP EP99964901A patent/EP1147404A1/en not_active Withdrawn
  • 1999-12-17 AU AU30931/00A patent/AU3093100A/en not_active Abandoned
  • 1999-12-17 JP JP2000591416A patent/JP2002533717A/ja not_active Withdrawn

Non-Patent Citations (1)

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