CA1219933A - Process and device for testing transparent material sheets - Google Patents
Process and device for testing transparent material sheetsInfo
- Publication number
- CA1219933A CA1219933A CA000408249A CA408249A CA1219933A CA 1219933 A CA1219933 A CA 1219933A CA 000408249 A CA000408249 A CA 000408249A CA 408249 A CA408249 A CA 408249A CA 1219933 A CA1219933 A CA 1219933A
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- CA
- Canada
- Prior art keywords
- sheet
- material sheet
- radiation
- pulses
- tested
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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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
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/892—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the flaw, defect or object feature examined
- G01N21/896—Optical defects in or on transparent materials, e.g. distortion, surface flaws in conveyed flat sheet or rod
-
- 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
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- 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 Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a method of testing transparent material sheets for flaws occluded in the sheet, such as foreign substances or gas bubbles, comprising scanning the material sheet with a flying light spot over its width, detecting transmitted and/or reflected radiation, detecting radiation emerg-ing laterally from the sheet, converting the detected radiation into electric signals, and evaluating the sheet with the aid of said signals.
The present invention provides a method of testing transparent material sheets for flaws occluded in the sheet, such as foreign substances or gas bubbles, comprising scanning the material sheet with a flying light spot over its width, detecting transmitted and/or reflected radiation, detecting radiation emerg-ing laterally from the sheet, converting the detected radiation into electric signals, and evaluating the sheet with the aid of said signals.
Description
~Z:~933 The present invention relates to a method and appara-tus for testing transparent ma-terial sheets, particularly flak glass, for flaws such as foreign substances or ~as bubbles trap ped in the sheet, in which the material sheet is scanned with a flying light spot over its width, and the transmitted and/or reflected radiation is intercepted, converted into e:lectric siy-nals, and evaluated.
In the present invention transparent material sheets includes plastics, organic glass and particularly sheet glass.
Since sheet glass is mechanically produced in large quantities as flat glass in the form of an endless belt, attempts are of course made to keep the sources of flaws as small as possible. The greatest need for testing equipment exists in the production of flat glass. The invention relates particularly to the examina-tion of flat glass but is not restricted thereto.
In the production of flat glass, for example, on float glass machinery it still happens that fine, usually bright, small stones infiltrate the glass sheet despite extreme precau-tions. Gas bubbles which are in the melt in a finely divided state constitute a further and also frequent flaw. On reaching a certain dimension these two flaws result in a surface defor-mation of the glass sheet although they are completely enclosed by the glass. Surface deformations can be readily determined by electrooptical testing devices and methods as described, for example, in the German Offenlegungsschrift 24 11 407. However, this does not apply to flaws which are so small that they do not change the surface of the glass sheet, particularly in the case of small core bubbles. These core bubbles are not detected by conventional devices, particularly when the surface tested is not 100~ clean.
The float glass is tested by scanning the entire width of the continuously moving material sheet with a flying light spot. In order to obtain a high luminous density, the flying light spot is usually produced by a laser, which is directed onto a rotating polygon reflector so that because of the high speed of the polygon the light beam sweeps the flat glass sheet at a high speed and thus forms the flying light spo-t. ~ portion oE
the beam is reflected at the surface of the glass sheet, a fur-ther portion enters the glass sheet and is reflected by the under-surface of the glass sheet, and the major portion of the beam passes through the glass sheet after reEraction.
It isan object of the present inventionto detect flaws in a transparent material sheet, which do not result in a surface deformation of the material sheet. Particularly, so-called core bubbles, i.e., gas bubbles,which are more or less at the centre of the material sheet and are very fine so that they are covered by the layers of the material sheet thick compared with the sizes of the gas bubbles,clre to be detected.
Accordingly, the present invention provides a method of testing transparent material sheets for flaws occluded in the sheet, such as foreign substances or gas bubbles, comprising scanning the material sheet with a flying light spot over its width, detecting transmitted and/or reflected radiation, detect-.ing radiation emerging laterally from the sheet, converting the detected radiation into electric signals, and evaluating the sheet with the aid of said signals.
Flaw-testing devices of the kind described in the Ger-man Offenlegungsschrift 24 11 407 scan with a flying light spot the width of a material sheet moving usually at a relatively high speed. The devices have an adjustable sensitivity, which makes it possible to detect both a flaw on the upperside and a flaw on the underside when scanning the material sheet from above.
Core bubbles trapped in the material sheet, even fine foreign substances do not result in a beam deflection as strong as that ~g~3 caused by deformation of the surface. The signal produced by these flaws is so weak that it corresponds to the signals caused by fine dust particles deposited on the material sheet. However, these signals are cut oEf in the evaluation station vf -the test-ing device. The threshold of this section is vertically adjust-able. The sensitivity th~ls is adjusted down to such an exte~t that impuri-ties on the surface do not result in a flaw signal.
However, when a core bubble or a fine small stone is present, the impinging light spot is deflected in the yas bubble or on the surface of the small stone. In this case the material sheet thus acts like a photoconductor. Since the core bubbles, i.e., the small gas bubbles, as well as the trapped small stones have a substantially spherical shape, the light beam impinging on them or entering them is reflected in a manner dependant on its la-teral motion and the angle of incidence changing therewith at least once parallel to the scanning line of the material sheet. It passes to the right or left lateral edge of the mater-ial sheet, where it is visible as a briefly flashing bright light spot.
However, data on the flaw per se cannot be provided as yet, i.e., the size of the flaw cannot be defined on the basis of this laterally flashing light spot. A decision as to whether this particular material sheet must be discarded or whether its use can still be justified because of the minimal size of the flaw cannot be made either. Therefore, the radiation emerging laterally from the sheet is intercepted, converted into pulses and used for controlling the evaluation unit, i.e., that at the instant when the light spot emerges on one or bo-th sides of the material sheet to be tested, the flaw can be localized and its size can be determined. The normal soiling of the surface of the material sheet to be tested does not result in a flaw indica-tion.
`` ~2~33 The flying light spot is suitably produced by a laser, since in this manner relatively high energies can be applied, i.e., relatively broad material sheets can be scanned up to the edge without power loss. According to a particularly preferred embodiment of the present invention the flying light spot has the colour of the material sheet to be tested. Conventional sheet glass has a slightly yreenish coloration due to slight traces of iron in the melt. However, this can be detected only when examining the faces of the sheet glass. Because of the relatively long path which the liyht spot must cover in the glass before it is visible laterally, the glass reacts like a colour filter, i.e., in the case of green coloration, incident red light, after covering a specific length of path, disappears, that is to say, it is filtered out. However, light having the same wavelength, which corresponds to the coloration of the glass, is not filtered out, but it is subject to the normal absorption and thus reaches the side faces with a smaller loss.
By employing a light source which radiates at the same colour as the material sheet to be tested it is possible to select a lower output of the light source and thus to save energy and material and simultaneously to ensure optimal efficiency.
However, all transparent materials absorb a certain proportion of light passing through them. This means that, in the case of the relatively broad flat glass sheets, whose width frequently exceeds 3 metres, in the presence of a core bubble, i.e., a gas bubble at the centre of the sheet, the light reflect-ed by this bubble must cover a path of approximately 1 50 m to one of the two sides before it can be absorbed by a photoelectric converter, generally by a photomultiplier. A substantial absorp-tion of light thus results, i.e., it is not possible to provideexact data on this flaw just detected without additional ampli-fication of the pulse emitted by the photomultiplier. However, when ~2~3.;~
-the ligh-t beam travels towards -the edge o the material shee-t an increasingly distinct flaw signal is obtained even when the size of -the flaw de-tec-ted and i-ts location in -the sheet axe iden-tical -to -the flaw at the centre oE the shee-t. ~'ur-therMore, -the ~act -that the material shee-t -to be tested, i.e., the float yl~ss, is never 100~ clean must also be considered. Thi~, rneans -that both the top side and -the bottom side can have du6 t particles, which can also cause a reElection of the beam into ~he ~lass. Fur-ther-more, a certain noise level is always present, and this noise level also varies. For example, when scanning the cen-tre of the sheet it is substantially lower than when scanning the sheet edge so tha-t-Elaws which are at the cen-tre of the sheet can be within the noise level a-t the sheet edge. It thus is important to suppress the noise level differentially to ensure tha-t a simi-lar and equally large flaw in -the edge region of the material shee-t emits the same pulses as a corresponding flaw in -the centre region of the ma-terial sheet.
Therefore, according to the present invention each electric lateral pulse as a function of the posi-tion oE the flying light spot scanning the transparent material sheet is compared with a selectable value assigned to this posi-tion, and on exceeding this va]ue a flaw signal is emit-ted.
A suitable embodiment of the present invention provides -tha-t the selectable value is fed into an electronic memory. This embodiment is par-ticularly suitable when only one material, for example, a single grade of glass, is -to be -tested so -that the material shee-t is no-t subjected to changes wi-th respect to bo-th the composition and the thickness. In this case it is sufficien-t to plot an absorption curve of the ma-terial and to store i-t.
In the present case -the -term electronic memories means semiconductor memories whiich differ according to the circuit technologies used. Memory types such as RAM, ROM, PROM, or EPROM
can be used in addition to shift registers. It has been found that the PROMs - programmable read only memories - are particular-ly suitable. The PROMs are fixed-value mernories whlch are pro-vided with the desired bit pattern after the production pxocess This can be done, for exarnple, by burning specific connectiorls within the memory. Thus, the program cannot be erascd, i.e., that after writing a program into a PROM it is no lvnger p~ssible to change the information and an accidental change of the kestiny program is not possible. In a second possibility of programming the PROMs the highly insulated gate electrodes are u-tilized.
The gate electrodes can be discharged by irradiation with UV
light and recharged by once more applying a correspondingly high voltage, i.eO, they can be programmed.
In the logic of the evaluating unit the value of the input pulse is compared with the ~alue of the stored pulses cor-responding to the scanning position oE the scanning beam and on exceeding the pulse value a flaw signal is released. Of course, it is also possible to employ several PROMs which correspond to different curves. This means that different material sheets can also be tested after preselecting the suitable memory. In this case RP~Is are also suitable as memories. These RAMs are not capable of retaining stored data over a lengthy period but they can be programmed as desired.
A preferred embodiment of the present invention is characterized in that a reference beam is separated from the scan-ning beam forming the Elying light spot and passed over a flaw-less reference strip of the transparent material strip to be test-ed. The light emerging at the lateral faces oE the reference strip is picked up and converted into pulses. These pulses are compared in their height with pulses obtained fxom the material to be tested.
This embodiment of the invention assures that exact -- 6 ~
-` ~IL2~33 values are always attained since the identical ma-terial sheet is used as the reference strip. Of course, it is also possible to use a reference strip which substantially corresponds to the material sheet to be tested, but is no-t completel~ identical thereto. However, in that case the fact that -the ~eference pulses obtained do not correspond 100~ lo the pul.~es obtain~d from ~h~
material sheet to be tested must be accep-ted, i.e., a certain tolerance limit must be accepted.
The lateral pulses are evaluated by means of a trigger threshold. For this purpose the absorption curve is stored in a PROM. This process is absolutely independent of the speed, and it is also free from overshots. By employing several PROMs it is possible to program also the testing of colored glass.
The lateral pulses are preferably evaluated by opposi-tion of polarity of the voltage obtained.
Any position of the flying light spot on the ma-terial sheet, provided the sheet is flawless, produces a pulse which is identical to the pulse produced from the reference strip by the separated reference beam at identical position of the flying light spot. In the flawless state the pulse values thus cancel each other. Therefore, no deflection results, whereas in the presence ~f a flaw the pulse values differ. Since the absorption of the glass is eliminated by the opposition of polarity of the voltages obtained, the extent of the flaw can be read from the extent of the pulses, i.e., that equal flaws now also result in equal flaw signals irrespectively of their position, i.e., re-gardless of their distance from the edge of the material sheet.
A device for carrying out the process suitably com-prises at least one testing instrument, which scans -the material sheet with a flying light spot, a receiver absorbing the reflect-ed and/or transmitted light, and an evaluating station assigned to the receiver. The evaluating station has at least one photo-multiplier disposed laterally of the material sheet to be tested.
The additional installation of a single photomultiplier on one longitudinal side of the transparent material sheet to be tested permits the detection o~ core bubbles. The devi~e use~
heretofore on a large scale, for example, a de~ice accordiny to the German Offenlegungsschrift 2~ 11 407, can be controlled via the additional photomultiplier and then ~sed ko detect core bubbles and occlusions in the glass sheet. The photomul-tiplier is then favourably disposed at the level of the scanning line traced by the flying light spot on the material sheet to be t,est-ed since the light beam entering the glass sheet is reflected to different sides, but the path parallel to the scanning line is the shortest path so that of all the points at which the light beam emerges in the region of the lateral edge of the material the region of the scanning line has the greatest brightness value and thus yields the strongest and clearest pulse.
A preferred device for carrying out the test is charac-terized in that the photomultiplier assigned to the face end of the material sheet to be tested is disposed above the longitud-inal edge of the material sheet to be tested and half a reflec-tor surface therebelow.
The light passed through a core bubble or an occlusion ~Z~33 in the material sheet emerges at the untreated material sheet edge, where it is scattered. Thus it passes ~owards the side as well as upwards and downwards so that in the ca~e of a p-~rel~ lateral arrangement of the photomultiplier it will be di~icult to pick up the light. However, by simply arranying a reflector surfa~e belo~
the longitudinal edge a large proportion of the arnounk of light emerging from the untreated face end of the material sheet is still picked up by the mirror and reflected to the photomultiplier dis-posed above the material sheet. The photomultiplier also is additionally acted upon with light emerging directly upwards. The picking-up of light thus is substantially improved.
In a favourable embodiment of the present invention a reference strip of a material, which corresponds in thickness, coloration,and composition to the transparent material sheet to be tested or is identical thereto and extends over the entire width of the transparent material sheet to be scanned is assigned to the testing device. On each of its narrow sides the reference strip is provided with a photoelectric converter. The narrow sides of said reference strip extend parallelly to the longitudin-al edges of the transparent material sheet to be tested but incontrast thereto they have been treated so that no undefined scat-tering occurs. Since the strips also are relatively narrow, the entire light emerging on these narrow sides can be picked up by the photoelectric converter.
However, the light enters this reference strip only after it has been subjected to a special preliminary treatment, i.e., in thenormal case, the light would pass through the glass as in the case of any flat glass and would not be so passed into -the glass that a substantial percentage thereof would emerge on the front ends, i~e., in the present case on the narrow sides of the reference strip.
Therefore, in a preferred development of the present g invention the re~erence strip is provided with notches er~ually spaced apart and extending in the longitudinal direction of the material sheet to be tested. The notches are a~vantageously sp~c~
ed apart by 5 to 10 mm. Because of -this arrangement pulses which correspond to the number of notches are ob-tained. Each pulse has a different value corresponding to its dis-tance frosn the centre of the material sheet since on approachiny the edge of the refer-ence strip, i.e., its narrow side, less light is absorbed and a higher signal thus is near the photoelectric converter.
By so arranging the notches that they are equally spac-ed apart this signal can be used simultaneously for determining the position of flaws and a mutual distance of 5 to 10 mm assures a substantial accuracy in the evaluation of the flaws.
In a further favourable development of the present inven-tion the reference strip is provided with a delustered line ex-tending over its entire length. This delustered line is suitably a sand-blasted area or a transparent adhesive strip applied to the reference strip. Both the sand-blasted strip and the trans-parent adhesive strip suitably applied below the reference strip permit the light to enter the reference strip and thus to be pass-ed on the narrow sides and to be absorbed in the photoelectric converter. However, in departure from the notches described above no current pulse is obtained in the converter, but when the light beam impinges on the reference strip, a specific voltage which varies in its value is obtained. This voltage has the lowest value when the flying light spot reaches the centre of the refer-ence strip, where the absorption is most intense. For this reason the reference strip is provided with photoelectric converters on both sides since only small amounts of light travel from one ma-terial sheet edge to the other. For each of the two converters acurve established by the converters begins at the centre of the material sheet with a value which is slightly above zero and with ~2~3;3 increasing proximity of the scanning light point it increases towards the sheet edge. For estimating the entire sheet wid-th the results of the two photoelectric converters, which ~omple-rrlent each other to the full curve, must be taken into account.
The present invention ~ill now be described in rnore detail, by way of e~arnple only, with reference to the accornpany~
ing drawings, in which:
Figure 1 is a diagrammatic sketch of a testing device;
Figure 2 shows the -testing apparatus with the reference strip being scanned;
Figure 3 shows the mirror arrangement at the edge in detail;
Figure 4 is a chart showing the individual pulses re-corded by the lateral photomultipliers; and Figure 5 is a chart showing the straight line resulting from superimposed curves of opposite polarity with a flaw signal.
The material sheet 1 is reciprocated under the testing device -2 by means of rollers 8 driven by an electric motor 9.
The testing device 2 contains a receiver 3 for reflected radia-tion and a receiver 3' for transmitted radiation. The two re-ceivers are connected to an evaluation unit 4, which is also acted upon by the photomultipliers 5, 5' laterally disposed with respect to the material sheet 1.
The laser 14 in the testing device 2 is provided with a beam splitter 30, which reflects two partial beams 31 and 32 on the rotating mirror drum 15. The partial beam 31 is reflected as the light spot 10' and the partial beam 32 as the light spot 10. Because of the rotation of the mirror drum 15 the light beam 32 is passed as a scanning beam 16 over the entire width of the material sheet 1. The partial beam 31 shown as the spot 10' is simultaneously passed over the reference strip 21 and enters it through the notch 24. A photoelectric converter 23 or ` ~2~3~
23' is assigned to each of the narrow sides 22 of the reference strip 21. The photoelectric converter receives the liyht emerg~
ing from the reference strip 21 and passes i^t on ~ ~e evaluation u~i-t ~.
If the material. sheet 1 contains a Elaw in the ~orrtl of a core bubble 13, the scanning beam 16 no lonyer reache.s the re-ceiver 3 as a reflected scanning beam 16', but is deflected as the light beam 11 and 12 and passed on the scanning line 7 to the face end 6 of the material sheet 1, where it enters the photomul-tipliers 5 and 5', which pass the pulse received to the evalu~tion unit 4. The photomultipliers 5, 5' are connected to the evalua-tion unit 4 by cables 17 and 18, and the photoelectric converters 23, 23' anologously by cables 33 and 34. Furthermore, an electric lead 19 extends from the receiver 3 to the evaluation unit 4.
As mentioned hereinbefore, when the scanning beam 16 impinges on a core bubble 13, the light is deflected from the core bubble 13 and emerges inthe region of the face end 6 of the ma-terial sheet 1. In the embodiment of Figure 3 there is disposed in the edge region o the material sheet 1 a substantially hori-zontally adjusted mirror 27 and a substantially vertically ad-justed mirror 28. 'rhe mirrors are arranged on a slidable support29 and the two mirrors are so aligned that they deElect light directed onto them into the photomultiplier 5 disposed above the edge region of the material sheet.
The partial beam 31 produces the light spot 10' on the rotating mirror drum 15. The reference beam 20 formed by the light spot scans 10' the reference strip 21 and enters it at the notches 24. A pulse is thus produced in the photoelectric conver-ter 23 by each notch 24. This pulse is recorded in the evaluation unit 4 and compared with the corresponding values determined by the photomultipliers 5, 5'. When the material sheet 1 is free from flaws the values determined are identical, i.e., they do not differ from each other. When using a reference strip 21, which has a ~2~33 delustered line or an adhesive strip, the evaluation is analoyous~The light passes along the delustered line or adhesive strip an~
enters the reference strip 21 and leaves it on i~s narrow side~
22, where it is received by the photoelectric converters 23. How-ever, a voltage which varies with the travel o the reference beam and can be plotted as a curve is obtained instead of a pulse.
Figure 4 shows an absorption curve 35, which was plotke~
along the spikes of the individual pulses 36 produced by the notch-es 24 in the reference strip 21 by the reference beam 20. The noise level curve 37 has been plotted below the absorption curve 35 in the same Figure. This noise level curve is caused substan-tially by impurities on the upper side and bottom side of the glass and is of no importance in the process accordiny to the present invention. However, it is clearly evident from the curve that the noise level is substantially higher in the edge region of the sheet so that flaws which can occur in the centre region of the sheet are superimposed by said noise level.
Figure 5 shows the opposite polarity of the absorption curve 3S, which was obtained via the reference strip 21 with underlying adhesive strips, with the scanning curve shown there-above. The scanning curve 38 has a flaw signal 39, which in its absolute height is smaller than the values in the edge region of the curve. The opposite polarity straight line 40 results from the opposite polarity. The flaw signal 39 distinctly projects from said straight line.
In the present invention transparent material sheets includes plastics, organic glass and particularly sheet glass.
Since sheet glass is mechanically produced in large quantities as flat glass in the form of an endless belt, attempts are of course made to keep the sources of flaws as small as possible. The greatest need for testing equipment exists in the production of flat glass. The invention relates particularly to the examina-tion of flat glass but is not restricted thereto.
In the production of flat glass, for example, on float glass machinery it still happens that fine, usually bright, small stones infiltrate the glass sheet despite extreme precau-tions. Gas bubbles which are in the melt in a finely divided state constitute a further and also frequent flaw. On reaching a certain dimension these two flaws result in a surface defor-mation of the glass sheet although they are completely enclosed by the glass. Surface deformations can be readily determined by electrooptical testing devices and methods as described, for example, in the German Offenlegungsschrift 24 11 407. However, this does not apply to flaws which are so small that they do not change the surface of the glass sheet, particularly in the case of small core bubbles. These core bubbles are not detected by conventional devices, particularly when the surface tested is not 100~ clean.
The float glass is tested by scanning the entire width of the continuously moving material sheet with a flying light spot. In order to obtain a high luminous density, the flying light spot is usually produced by a laser, which is directed onto a rotating polygon reflector so that because of the high speed of the polygon the light beam sweeps the flat glass sheet at a high speed and thus forms the flying light spo-t. ~ portion oE
the beam is reflected at the surface of the glass sheet, a fur-ther portion enters the glass sheet and is reflected by the under-surface of the glass sheet, and the major portion of the beam passes through the glass sheet after reEraction.
It isan object of the present inventionto detect flaws in a transparent material sheet, which do not result in a surface deformation of the material sheet. Particularly, so-called core bubbles, i.e., gas bubbles,which are more or less at the centre of the material sheet and are very fine so that they are covered by the layers of the material sheet thick compared with the sizes of the gas bubbles,clre to be detected.
Accordingly, the present invention provides a method of testing transparent material sheets for flaws occluded in the sheet, such as foreign substances or gas bubbles, comprising scanning the material sheet with a flying light spot over its width, detecting transmitted and/or reflected radiation, detect-.ing radiation emerging laterally from the sheet, converting the detected radiation into electric signals, and evaluating the sheet with the aid of said signals.
Flaw-testing devices of the kind described in the Ger-man Offenlegungsschrift 24 11 407 scan with a flying light spot the width of a material sheet moving usually at a relatively high speed. The devices have an adjustable sensitivity, which makes it possible to detect both a flaw on the upperside and a flaw on the underside when scanning the material sheet from above.
Core bubbles trapped in the material sheet, even fine foreign substances do not result in a beam deflection as strong as that ~g~3 caused by deformation of the surface. The signal produced by these flaws is so weak that it corresponds to the signals caused by fine dust particles deposited on the material sheet. However, these signals are cut oEf in the evaluation station vf -the test-ing device. The threshold of this section is vertically adjust-able. The sensitivity th~ls is adjusted down to such an exte~t that impuri-ties on the surface do not result in a flaw signal.
However, when a core bubble or a fine small stone is present, the impinging light spot is deflected in the yas bubble or on the surface of the small stone. In this case the material sheet thus acts like a photoconductor. Since the core bubbles, i.e., the small gas bubbles, as well as the trapped small stones have a substantially spherical shape, the light beam impinging on them or entering them is reflected in a manner dependant on its la-teral motion and the angle of incidence changing therewith at least once parallel to the scanning line of the material sheet. It passes to the right or left lateral edge of the mater-ial sheet, where it is visible as a briefly flashing bright light spot.
However, data on the flaw per se cannot be provided as yet, i.e., the size of the flaw cannot be defined on the basis of this laterally flashing light spot. A decision as to whether this particular material sheet must be discarded or whether its use can still be justified because of the minimal size of the flaw cannot be made either. Therefore, the radiation emerging laterally from the sheet is intercepted, converted into pulses and used for controlling the evaluation unit, i.e., that at the instant when the light spot emerges on one or bo-th sides of the material sheet to be tested, the flaw can be localized and its size can be determined. The normal soiling of the surface of the material sheet to be tested does not result in a flaw indica-tion.
`` ~2~33 The flying light spot is suitably produced by a laser, since in this manner relatively high energies can be applied, i.e., relatively broad material sheets can be scanned up to the edge without power loss. According to a particularly preferred embodiment of the present invention the flying light spot has the colour of the material sheet to be tested. Conventional sheet glass has a slightly yreenish coloration due to slight traces of iron in the melt. However, this can be detected only when examining the faces of the sheet glass. Because of the relatively long path which the liyht spot must cover in the glass before it is visible laterally, the glass reacts like a colour filter, i.e., in the case of green coloration, incident red light, after covering a specific length of path, disappears, that is to say, it is filtered out. However, light having the same wavelength, which corresponds to the coloration of the glass, is not filtered out, but it is subject to the normal absorption and thus reaches the side faces with a smaller loss.
By employing a light source which radiates at the same colour as the material sheet to be tested it is possible to select a lower output of the light source and thus to save energy and material and simultaneously to ensure optimal efficiency.
However, all transparent materials absorb a certain proportion of light passing through them. This means that, in the case of the relatively broad flat glass sheets, whose width frequently exceeds 3 metres, in the presence of a core bubble, i.e., a gas bubble at the centre of the sheet, the light reflect-ed by this bubble must cover a path of approximately 1 50 m to one of the two sides before it can be absorbed by a photoelectric converter, generally by a photomultiplier. A substantial absorp-tion of light thus results, i.e., it is not possible to provideexact data on this flaw just detected without additional ampli-fication of the pulse emitted by the photomultiplier. However, when ~2~3.;~
-the ligh-t beam travels towards -the edge o the material shee-t an increasingly distinct flaw signal is obtained even when the size of -the flaw de-tec-ted and i-ts location in -the sheet axe iden-tical -to -the flaw at the centre oE the shee-t. ~'ur-therMore, -the ~act -that the material shee-t -to be tested, i.e., the float yl~ss, is never 100~ clean must also be considered. Thi~, rneans -that both the top side and -the bottom side can have du6 t particles, which can also cause a reElection of the beam into ~he ~lass. Fur-ther-more, a certain noise level is always present, and this noise level also varies. For example, when scanning the cen-tre of the sheet it is substantially lower than when scanning the sheet edge so tha-t-Elaws which are at the cen-tre of the sheet can be within the noise level a-t the sheet edge. It thus is important to suppress the noise level differentially to ensure tha-t a simi-lar and equally large flaw in -the edge region of the material shee-t emits the same pulses as a corresponding flaw in -the centre region of the ma-terial sheet.
Therefore, according to the present invention each electric lateral pulse as a function of the posi-tion oE the flying light spot scanning the transparent material sheet is compared with a selectable value assigned to this posi-tion, and on exceeding this va]ue a flaw signal is emit-ted.
A suitable embodiment of the present invention provides -tha-t the selectable value is fed into an electronic memory. This embodiment is par-ticularly suitable when only one material, for example, a single grade of glass, is -to be -tested so -that the material shee-t is no-t subjected to changes wi-th respect to bo-th the composition and the thickness. In this case it is sufficien-t to plot an absorption curve of the ma-terial and to store i-t.
In the present case -the -term electronic memories means semiconductor memories whiich differ according to the circuit technologies used. Memory types such as RAM, ROM, PROM, or EPROM
can be used in addition to shift registers. It has been found that the PROMs - programmable read only memories - are particular-ly suitable. The PROMs are fixed-value mernories whlch are pro-vided with the desired bit pattern after the production pxocess This can be done, for exarnple, by burning specific connectiorls within the memory. Thus, the program cannot be erascd, i.e., that after writing a program into a PROM it is no lvnger p~ssible to change the information and an accidental change of the kestiny program is not possible. In a second possibility of programming the PROMs the highly insulated gate electrodes are u-tilized.
The gate electrodes can be discharged by irradiation with UV
light and recharged by once more applying a correspondingly high voltage, i.eO, they can be programmed.
In the logic of the evaluating unit the value of the input pulse is compared with the ~alue of the stored pulses cor-responding to the scanning position oE the scanning beam and on exceeding the pulse value a flaw signal is released. Of course, it is also possible to employ several PROMs which correspond to different curves. This means that different material sheets can also be tested after preselecting the suitable memory. In this case RP~Is are also suitable as memories. These RAMs are not capable of retaining stored data over a lengthy period but they can be programmed as desired.
A preferred embodiment of the present invention is characterized in that a reference beam is separated from the scan-ning beam forming the Elying light spot and passed over a flaw-less reference strip of the transparent material strip to be test-ed. The light emerging at the lateral faces oE the reference strip is picked up and converted into pulses. These pulses are compared in their height with pulses obtained fxom the material to be tested.
This embodiment of the invention assures that exact -- 6 ~
-` ~IL2~33 values are always attained since the identical ma-terial sheet is used as the reference strip. Of course, it is also possible to use a reference strip which substantially corresponds to the material sheet to be tested, but is no-t completel~ identical thereto. However, in that case the fact that -the ~eference pulses obtained do not correspond 100~ lo the pul.~es obtain~d from ~h~
material sheet to be tested must be accep-ted, i.e., a certain tolerance limit must be accepted.
The lateral pulses are evaluated by means of a trigger threshold. For this purpose the absorption curve is stored in a PROM. This process is absolutely independent of the speed, and it is also free from overshots. By employing several PROMs it is possible to program also the testing of colored glass.
The lateral pulses are preferably evaluated by opposi-tion of polarity of the voltage obtained.
Any position of the flying light spot on the ma-terial sheet, provided the sheet is flawless, produces a pulse which is identical to the pulse produced from the reference strip by the separated reference beam at identical position of the flying light spot. In the flawless state the pulse values thus cancel each other. Therefore, no deflection results, whereas in the presence ~f a flaw the pulse values differ. Since the absorption of the glass is eliminated by the opposition of polarity of the voltages obtained, the extent of the flaw can be read from the extent of the pulses, i.e., that equal flaws now also result in equal flaw signals irrespectively of their position, i.e., re-gardless of their distance from the edge of the material sheet.
A device for carrying out the process suitably com-prises at least one testing instrument, which scans -the material sheet with a flying light spot, a receiver absorbing the reflect-ed and/or transmitted light, and an evaluating station assigned to the receiver. The evaluating station has at least one photo-multiplier disposed laterally of the material sheet to be tested.
The additional installation of a single photomultiplier on one longitudinal side of the transparent material sheet to be tested permits the detection o~ core bubbles. The devi~e use~
heretofore on a large scale, for example, a de~ice accordiny to the German Offenlegungsschrift 2~ 11 407, can be controlled via the additional photomultiplier and then ~sed ko detect core bubbles and occlusions in the glass sheet. The photomul-tiplier is then favourably disposed at the level of the scanning line traced by the flying light spot on the material sheet to be t,est-ed since the light beam entering the glass sheet is reflected to different sides, but the path parallel to the scanning line is the shortest path so that of all the points at which the light beam emerges in the region of the lateral edge of the material the region of the scanning line has the greatest brightness value and thus yields the strongest and clearest pulse.
A preferred device for carrying out the test is charac-terized in that the photomultiplier assigned to the face end of the material sheet to be tested is disposed above the longitud-inal edge of the material sheet to be tested and half a reflec-tor surface therebelow.
The light passed through a core bubble or an occlusion ~Z~33 in the material sheet emerges at the untreated material sheet edge, where it is scattered. Thus it passes ~owards the side as well as upwards and downwards so that in the ca~e of a p-~rel~ lateral arrangement of the photomultiplier it will be di~icult to pick up the light. However, by simply arranying a reflector surfa~e belo~
the longitudinal edge a large proportion of the arnounk of light emerging from the untreated face end of the material sheet is still picked up by the mirror and reflected to the photomultiplier dis-posed above the material sheet. The photomultiplier also is additionally acted upon with light emerging directly upwards. The picking-up of light thus is substantially improved.
In a favourable embodiment of the present invention a reference strip of a material, which corresponds in thickness, coloration,and composition to the transparent material sheet to be tested or is identical thereto and extends over the entire width of the transparent material sheet to be scanned is assigned to the testing device. On each of its narrow sides the reference strip is provided with a photoelectric converter. The narrow sides of said reference strip extend parallelly to the longitudin-al edges of the transparent material sheet to be tested but incontrast thereto they have been treated so that no undefined scat-tering occurs. Since the strips also are relatively narrow, the entire light emerging on these narrow sides can be picked up by the photoelectric converter.
However, the light enters this reference strip only after it has been subjected to a special preliminary treatment, i.e., in thenormal case, the light would pass through the glass as in the case of any flat glass and would not be so passed into -the glass that a substantial percentage thereof would emerge on the front ends, i~e., in the present case on the narrow sides of the reference strip.
Therefore, in a preferred development of the present g invention the re~erence strip is provided with notches er~ually spaced apart and extending in the longitudinal direction of the material sheet to be tested. The notches are a~vantageously sp~c~
ed apart by 5 to 10 mm. Because of -this arrangement pulses which correspond to the number of notches are ob-tained. Each pulse has a different value corresponding to its dis-tance frosn the centre of the material sheet since on approachiny the edge of the refer-ence strip, i.e., its narrow side, less light is absorbed and a higher signal thus is near the photoelectric converter.
By so arranging the notches that they are equally spac-ed apart this signal can be used simultaneously for determining the position of flaws and a mutual distance of 5 to 10 mm assures a substantial accuracy in the evaluation of the flaws.
In a further favourable development of the present inven-tion the reference strip is provided with a delustered line ex-tending over its entire length. This delustered line is suitably a sand-blasted area or a transparent adhesive strip applied to the reference strip. Both the sand-blasted strip and the trans-parent adhesive strip suitably applied below the reference strip permit the light to enter the reference strip and thus to be pass-ed on the narrow sides and to be absorbed in the photoelectric converter. However, in departure from the notches described above no current pulse is obtained in the converter, but when the light beam impinges on the reference strip, a specific voltage which varies in its value is obtained. This voltage has the lowest value when the flying light spot reaches the centre of the refer-ence strip, where the absorption is most intense. For this reason the reference strip is provided with photoelectric converters on both sides since only small amounts of light travel from one ma-terial sheet edge to the other. For each of the two converters acurve established by the converters begins at the centre of the material sheet with a value which is slightly above zero and with ~2~3;3 increasing proximity of the scanning light point it increases towards the sheet edge. For estimating the entire sheet wid-th the results of the two photoelectric converters, which ~omple-rrlent each other to the full curve, must be taken into account.
The present invention ~ill now be described in rnore detail, by way of e~arnple only, with reference to the accornpany~
ing drawings, in which:
Figure 1 is a diagrammatic sketch of a testing device;
Figure 2 shows the -testing apparatus with the reference strip being scanned;
Figure 3 shows the mirror arrangement at the edge in detail;
Figure 4 is a chart showing the individual pulses re-corded by the lateral photomultipliers; and Figure 5 is a chart showing the straight line resulting from superimposed curves of opposite polarity with a flaw signal.
The material sheet 1 is reciprocated under the testing device -2 by means of rollers 8 driven by an electric motor 9.
The testing device 2 contains a receiver 3 for reflected radia-tion and a receiver 3' for transmitted radiation. The two re-ceivers are connected to an evaluation unit 4, which is also acted upon by the photomultipliers 5, 5' laterally disposed with respect to the material sheet 1.
The laser 14 in the testing device 2 is provided with a beam splitter 30, which reflects two partial beams 31 and 32 on the rotating mirror drum 15. The partial beam 31 is reflected as the light spot 10' and the partial beam 32 as the light spot 10. Because of the rotation of the mirror drum 15 the light beam 32 is passed as a scanning beam 16 over the entire width of the material sheet 1. The partial beam 31 shown as the spot 10' is simultaneously passed over the reference strip 21 and enters it through the notch 24. A photoelectric converter 23 or ` ~2~3~
23' is assigned to each of the narrow sides 22 of the reference strip 21. The photoelectric converter receives the liyht emerg~
ing from the reference strip 21 and passes i^t on ~ ~e evaluation u~i-t ~.
If the material. sheet 1 contains a Elaw in the ~orrtl of a core bubble 13, the scanning beam 16 no lonyer reache.s the re-ceiver 3 as a reflected scanning beam 16', but is deflected as the light beam 11 and 12 and passed on the scanning line 7 to the face end 6 of the material sheet 1, where it enters the photomul-tipliers 5 and 5', which pass the pulse received to the evalu~tion unit 4. The photomultipliers 5, 5' are connected to the evalua-tion unit 4 by cables 17 and 18, and the photoelectric converters 23, 23' anologously by cables 33 and 34. Furthermore, an electric lead 19 extends from the receiver 3 to the evaluation unit 4.
As mentioned hereinbefore, when the scanning beam 16 impinges on a core bubble 13, the light is deflected from the core bubble 13 and emerges inthe region of the face end 6 of the ma-terial sheet 1. In the embodiment of Figure 3 there is disposed in the edge region o the material sheet 1 a substantially hori-zontally adjusted mirror 27 and a substantially vertically ad-justed mirror 28. 'rhe mirrors are arranged on a slidable support29 and the two mirrors are so aligned that they deElect light directed onto them into the photomultiplier 5 disposed above the edge region of the material sheet.
The partial beam 31 produces the light spot 10' on the rotating mirror drum 15. The reference beam 20 formed by the light spot scans 10' the reference strip 21 and enters it at the notches 24. A pulse is thus produced in the photoelectric conver-ter 23 by each notch 24. This pulse is recorded in the evaluation unit 4 and compared with the corresponding values determined by the photomultipliers 5, 5'. When the material sheet 1 is free from flaws the values determined are identical, i.e., they do not differ from each other. When using a reference strip 21, which has a ~2~33 delustered line or an adhesive strip, the evaluation is analoyous~The light passes along the delustered line or adhesive strip an~
enters the reference strip 21 and leaves it on i~s narrow side~
22, where it is received by the photoelectric converters 23. How-ever, a voltage which varies with the travel o the reference beam and can be plotted as a curve is obtained instead of a pulse.
Figure 4 shows an absorption curve 35, which was plotke~
along the spikes of the individual pulses 36 produced by the notch-es 24 in the reference strip 21 by the reference beam 20. The noise level curve 37 has been plotted below the absorption curve 35 in the same Figure. This noise level curve is caused substan-tially by impurities on the upper side and bottom side of the glass and is of no importance in the process accordiny to the present invention. However, it is clearly evident from the curve that the noise level is substantially higher in the edge region of the sheet so that flaws which can occur in the centre region of the sheet are superimposed by said noise level.
Figure 5 shows the opposite polarity of the absorption curve 3S, which was obtained via the reference strip 21 with underlying adhesive strips, with the scanning curve shown there-above. The scanning curve 38 has a flaw signal 39, which in its absolute height is smaller than the values in the edge region of the curve. The opposite polarity straight line 40 results from the opposite polarity. The flaw signal 39 distinctly projects from said straight line.
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of testing transparent material sheets for flaws occluded in the sheet, such as foreign substances of gas bubbles, comprising scanning the material sheet with a flying light spot over its width, detecting transmitted and/
or reflected radiation, detecting radiation emerging later-ally from the sheet, converting the detected radiation into electric signals, and evaluating the sheet with the aid of said signals, the electric signals representing the laterally emer-ging radiation being in the form of pulses representing flashes of radiation corresponding to the presence of flaws or occlu-sions, each pulse being compared with a value assigned to the current position of the flying light spot, and on exceeding this value a flaw signal being generated.
or reflected radiation, detecting radiation emerging later-ally from the sheet, converting the detected radiation into electric signals, and evaluating the sheet with the aid of said signals, the electric signals representing the laterally emer-ging radiation being in the form of pulses representing flashes of radiation corresponding to the presence of flaws or occlu-sions, each pulse being compared with a value assigned to the current position of the flying light spot, and on exceeding this value a flaw signal being generated.
2. A method according to claim 1, wherein the flying light spot is produced by a laser.
3. A method according to claim 1, wherein the flying light spot has the colour of the material sheet to be tested.
4. A method according to claim 1, wherein predeter-mined assigned values are stored in an electronic memory.
5. A method according to claim 1, wherein a reference beam is separated from the scanning beam forming the flying light spot and passed onto a flawless reference strip, the light emerging at the lateral faces of the reference strip is detected and converted into pulses, and these pulses are compared in their values with the pulses obtained from the material sheet to be tested.
6. A process according to any of claims 1 to 3, wherein the lateral pulses are evaluated by means of a trigger threshold.
7. A process according to claim 5, wherein the evaluation of the lateral pulses is carried out by superim-posing pulses of opposite polarity from the reference strip and the material to be tested so that the pulses cancel each other except where a flaw is present.
8. A method as claimed in any of claims 1 to 3, wherein the material sheets are flat glass.
9. An apparatus for testing material sheets for flaws occluded in the sheet, such as foreign substances or gas bub-bles, comprising at least one testing device scanning the material sheet with a flying light spot, a receiver absorbing the reflected and/or the transmitted light, at least one detec-tor for receiving radiation emitted laterally through at least one end face of the material sheet to be tested, said detector being disposed at the level of the scanning line traced by the flying light spot on the material sheet to be tested, and an evaluation unit for evaluating the sheet on the basis of the radiation detected.
10. An apparatus as claimed in claim 9, wherein the detector for lateral radiation includes a photomultiplier.
11. An apparatus according to claim 10. wherein the photomultiplier is disposed above the longitudinal edge of the transparent material sheet, and at least one reflector surface is provided at the edge of the sheet to reflect radiation emerging through said edge onto the photomultiplier.
12. An apparatus according to claim 9, further com-prising a reference strip of a flawless material, which, in thickness, coloration and composition, corresponds or is identical to the transparent material sheet to be tested, and extending over the entire width of the transparent material sheet to be scanned, and at least one detection for detecting radiation emerging laterally through at least one end face of the reference strip.
13. An apparatus according to claim 12, wherein the reference strip is provided with equally spaced notches extend-ing in the longitudinal direction of the material sheet to be tested.
14. An apparatus according to claim 13, wherein the notches are spaced apart by 5 to 10 mm.
15. An apparatus according to claim 12, wherein the reference strip is provided with a delustered line extending over its entire length.
16. An apparatus according to claim 15, wherein the delustered line is produced by sandblasting.
17. An apparatus according to claim 15 or 16, wherein the delustered line is produced by applying a transparent adhesive strip.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3129808A DE3129808C2 (en) | 1981-07-29 | 1981-07-29 | Method for testing transparent material webs |
| DEP3129808.7-52 | 1981-07-29 | ||
| DE19823223215 DE3223215A1 (en) | 1982-06-22 | 1982-06-22 | Method and device for testing transparent material webs |
| DEP3223215.2 | 1982-06-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219933A true CA1219933A (en) | 1987-03-31 |
Family
ID=25794894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408249A Expired CA1219933A (en) | 1981-07-29 | 1982-07-28 | Process and device for testing transparent material sheets |
Country Status (12)
| Country | Link |
|---|---|
| EP (1) | EP0071257B1 (en) |
| KR (1) | KR870001703B1 (en) |
| AU (1) | AU536514B2 (en) |
| BR (1) | BR8204412A (en) |
| CA (1) | CA1219933A (en) |
| CS (1) | CS241114B2 (en) |
| DD (1) | DD202470A5 (en) |
| DE (1) | DE3262426D1 (en) |
| DK (1) | DK334682A (en) |
| ES (1) | ES8305929A1 (en) |
| FI (1) | FI74148C (en) |
| SU (1) | SU1276268A3 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5157266A (en) * | 1988-02-29 | 1992-10-20 | Stora Feldmuehle Aktiengesellschaft | Method and device for testing transparent sheets |
| US9316596B2 (en) | 2011-08-19 | 2016-04-19 | Industries Machinex Inc. | Apparatus and method for inspecting matter and use thereof for sorting recyclable matter |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ATE38289T1 (en) * | 1984-12-14 | 1988-11-15 | Flachglas Ag | METHOD AND DEVICE FOR TESTING TRANSPARENT MATERIAL WEBS, IN PARTICULAR FLAT GLASS RIBBON. |
| US5724140A (en) * | 1996-10-28 | 1998-03-03 | Ford Motor Company | Method and apparatus for determining the quality of flat glass sheet |
| EA008773B1 (en) * | 2006-05-19 | 2007-08-31 | Владимир Федорович Солинов | Method for detecting defects in sheet glass |
| CN107703094B (en) * | 2017-09-27 | 2021-03-26 | 安徽中科光电色选机械有限公司 | Near-infrared multispectral sorting equipment |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1315654A (en) * | 1969-05-21 | 1973-05-02 | Pilkington Brothers Ltd | Detection of faults in transparent material using lasers |
| FR2187118A5 (en) * | 1972-05-30 | 1974-01-11 | Saint Gobain Pont A Mousson | Testing glass sheet for defects - using a laser beam injected via the edge of the glass |
| US3871773A (en) * | 1973-04-24 | 1975-03-18 | Ppg Industries Inc | Method of and apparatus for detecting defects and the position thereof in transparent articles |
| SE7502440L (en) * | 1974-03-09 | 1975-09-10 | Feldmuehle Anlagen Prod |
-
1982
- 1982-07-16 CS CS825476A patent/CS241114B2/en unknown
- 1982-07-27 DK DK334682A patent/DK334682A/en not_active Application Discontinuation
- 1982-07-27 DD DD82241984A patent/DD202470A5/en unknown
- 1982-07-27 AU AU86447/82A patent/AU536514B2/en not_active Ceased
- 1982-07-28 ES ES514466A patent/ES8305929A1/en not_active Expired
- 1982-07-28 CA CA000408249A patent/CA1219933A/en not_active Expired
- 1982-07-28 EP EP82106817A patent/EP0071257B1/en not_active Expired
- 1982-07-28 DE DE8282106817T patent/DE3262426D1/en not_active Expired
- 1982-07-28 FI FI822637A patent/FI74148C/en not_active IP Right Cessation
- 1982-07-28 BR BR8204412A patent/BR8204412A/en not_active IP Right Cessation
- 1982-07-28 SU SU823467495A patent/SU1276268A3/en active
- 1982-07-29 KR KR8203391A patent/KR870001703B1/en active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5157266A (en) * | 1988-02-29 | 1992-10-20 | Stora Feldmuehle Aktiengesellschaft | Method and device for testing transparent sheets |
| US9316596B2 (en) | 2011-08-19 | 2016-04-19 | Industries Machinex Inc. | Apparatus and method for inspecting matter and use thereof for sorting recyclable matter |
Also Published As
| Publication number | Publication date |
|---|---|
| CS241114B2 (en) | 1986-03-13 |
| DD202470A5 (en) | 1983-09-14 |
| DK334682A (en) | 1983-01-30 |
| SU1276268A3 (en) | 1986-12-07 |
| ES514466A0 (en) | 1983-04-16 |
| DE3262426D1 (en) | 1985-03-28 |
| FI822637L (en) | 1983-01-30 |
| BR8204412A (en) | 1983-07-19 |
| FI822637A0 (en) | 1982-07-28 |
| EP0071257B1 (en) | 1985-02-20 |
| FI74148C (en) | 1987-12-10 |
| ES8305929A1 (en) | 1983-04-16 |
| KR870001703B1 (en) | 1987-09-24 |
| AU8644782A (en) | 1983-02-03 |
| FI74148B (en) | 1987-08-31 |
| EP0071257A1 (en) | 1983-02-09 |
| KR840000802A (en) | 1984-02-27 |
| CS547682A2 (en) | 1985-07-16 |
| AU536514B2 (en) | 1984-05-10 |
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