Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
• • 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
  • G01N21/8901—Optical details; Scanning details

Definitions

• the present invention relates to a method and a device for contactless testing of various test items.
• These can be the surfaces of test goods or their spatial interior.
• the supposedly smooth or regularly structured surfaces are checked for irregularities, or a translucent, supposedly uniformly or regularly structured layer of a material is checked for irregularities.
• irregularities can occur, for example, as a result of inclusions.
• web materials that run in the manufacturing process or in a treatment process for example a film or textile fabric web, and which run through have a surface that is supposed to remain calm
• the degree of smoothness can be determined or any irregularities in smoothness can be determined.
• Such tests are necessary as part of various treatment processes such as lamination or vapor deposition.
• Another disadvantage of the previously known systems is that the entire scanned information is in serial form.
• the measuring device therefore eats line by line and interrelates the determined data in a series.
• This series of measurement data must then be assigned to the individual measurement points by means of a transformation, which requires a very wide range of evaluation devices and also usually places high demands on the evaluation software.
• the lack of redundancy of the systems is also disadvantageous. Failure of a single important part, such as the laser, leads to failure of the entire system.
• the object of the present invention is therefore to create a method and a device which overcomes the disadvantages mentioned and in particular also allows the testing of complicatedly shaped materials, the testing device being adaptable to the requirements of the test material in a predeterminable manner , or can be automatically adjusted in the process flow.
• This object is achieved by a method according to the preamble and the characterizing features of patent claim 1, and by a device for carrying out the method with the features of patent claim 3.
• the method according to the invention and the devices for its practice enable simultaneous contactless testing of a surface or an inner boundary surface of a material to be tested by means of incident light which is reflected on the surface or on an inner boundary surface and is subsequently detected. But also a spatial layer or a spatial portion of a material ', or its internal structure can be checked by the incident light is scattered and it is detected thereafter.
• Figure 1 shows the principle of operation of the method for testing a surface and the internal structure of a test material
• Figures 2-5 show four basic variants of the method
• FIG. 6 shows the functional principle of the method for testing a test material with an irregular material thickness
• FIG. 7 shows a diagram of a first exemplary possibility of a device for controlling the light intensity of a light source section
• Figure. 8 shows a schematic of a second exemplary possibility of a device for controlling the light intensity of a light source section
• FIG. 9 shows a diagram of a first exemplary possibility of a device for determining the light intensity in the light receiver
• Figure 10 shows a schematic of a second example of a device for determining the light intensity at the light receiver.
• FIG. 1 shows the basic functional principle of the method according to the invention for testing a surface and / or the internal structure of a test material using one schematically shown device for its exercise ge shows.
• the test material 1 consists of a material which is, for example, a web material whose surface is to be tested, or it can be a transparent or translucent material in which the inner structure is also to be tested in addition to the surface.
• the test material moves from right to left according to the arrow drawn in with a uniform movement. According to the invention, it is now illuminated by light from a directed, linear light source 2, as indicated by the corresponding arrows.
• the light striking the test material 1 in the form of a light bar 3 is reflected to a part on the test material 1, which depends on the material and in particular its surface quality.
• the reflected part of the light is again detected on a line-shaped, optoelectronic transducer arrangement 4 as a light bar.
• the non-reflected part of the light penetrates the test material 1, is scattered thereon and emerges from the test material 1 on the other, here lower side. Further reflection is possible at the lower interface of the test material 1.
• the emerging light is finally detected by a further line-shaped, optoelectronic transducer arrangement 5.
• the intensities of the detected light are measured in the individual points of the linear optoelectronic transducer arrangements 4, 5.
• these converter arrangements 4, 5 must have the highest possible optical resolution. For this reason, they are made up of a number of individual optical elements 6, which are designed in such a way that together they form a linear field of view.
• the light source 2 is also constructed from such individual optical elements 7, which can then be controlled separately with respect to the intensity of the light emitted by them. Due to the separate, individual control of the light intensity of each light point and the separate, individual determination of the detected intensity at each measurement point, a specific light intensity can be selected practically for each measurement point or the values to be detected can be specified as parameters.
• location-dependent intensity values corresponding to the movement of the movement of the test material 1 can then be specified empirically or mathematically for each point, which then serve as measurement parameters.
• Means can also be provided by means of which an empirically or mathematically defined, location-dependent course of the intensity of the light to be detected can be predetermined for each point of the light bar when the test material is passed over. The values can be fed back and compared. A movement inspection of the surface running through can be carried out by identifying a specific intensity course.
• FIGS. 2 to 5 show four different variants of how the method according to the invention can be used.
• FIG. 2 shows the most simple variant, in which the light source 2 is an opaque material 1 illuminates. Part of the incident light is reflected on its surface, the rest is absorbed in the material. The reflected portion is from the detector 4, the optoelectronic. Transducer arrangement, detected.
• This arrangement can be used, for example, to check the surface of film material, the film material running in the form of a web under the light bar 3.
• the arrangement is also suitable for checking the surface of solid surfaces such as body parts, metal fittings or similar materials with light-reflecting surfaces. Widths up to 10 meters can be checked using in-line inspection.
• the error resolution is, for example, approximately 10 ⁇ m for holes, so-called “pin holes”, in thinly rolled surface layers.
• a resolution of about 50 ⁇ m is achieved.
• coating defects, foreign particles (dust), scratches, pressure marks, depressions and holes in particular can be detected. Changes in density, color, surface roughness and surface quality can also be detected.
• the test method according to the invention allows high test speeds of up to 17 m / s belt speed.
• FIG. 3 shows a variant in which the test material 1 is transparent or translucent, ie diffusely translucent. Part of the light emitted by the light source 2 and incident on the test material 1 is reflected, the other part penetrates the test material 1 except for absorption losses and after it emerges from the test material 1 is reflected on a mirror 8, from which it again penetrates the test material 1.
• the two light beam bands are finally detected with the optoelectronic transducer arrangement 4.
• This arrangement allows the surface and at the same time the structure of the translucent material to be checked.
• inclusions (bubbles) and their size can be determined, for example, or the regularity of cross-linking 1 s, the tensile force connections in the interior of polymers, can be checked. Variations in color and transmission can also be determined.
• Figure 4 shows an arrangement for the inspection of surfaces. Part of the light is reflected on the surface, while the part of the light penetrating the test material 1 is reflected on the opposite surface 9 or at the interface formed by it, and is detected after the test material 1 has penetrated again. The part that is not reflected at the interface is collected by an absorber 10, for example black velvet.
• FIG. 5 shows an arrangement as it is used to test the boundary layer 13 between two adjacent materials 11, 12, for example a laminate.
• the light penetrates the first, here upper material 11 and is largely reflected at the interface 13 with the second, here lower material 12.
• the reflected light penetrates again the first material 11 and is detected after it emerges.
• the light not reflected at the interface 13 penetrates the second material 12 and light emerging from its surface 14 is collected by an absorber 10. Increased transmitted light can indicate laminate defects.
• FIG. 6 shows the functional principle of the method for testing a test material 1 with an irregular material thickness.
• a light band is generated on the test material 1, which has an intensity profile I which corresponds to the profile of the Light attenuation in the test material 1 see above. corresponds to the fact that this is compensated.
• An optoelectronic transducer arrangement 6 and an optical element 7 each form a so-called measuring channel.
• FIG. 7 shows a diagram of a first exemplary possibility of a device for location-dependent and program-controlled control of the light intensity of a light source section.
• the linear light source as a whole here consists of a large number of discrete light sources, all of which here each have a light-emitting diode (LED ) 15 or a laser. Each individual light source of this type forms a light section, which can be individually controlled in its intensity.
• the control takes place via a control channel (control bus) 16 connecting all the individual light sources.
• the circuit shown thus shows the circuit of an individual light source.
• the circuit is supplied with power (power PWR) via line 17.
• control signals are processed in a logic circuit LOGIC 18 and output to the AC driver 20 via the digital-to-analog converter (DAC) 19. This then feeds the light emitting diode (LED) or a laser.
• DAC digital-to-analog converter
• a back light receiver 21 is coupled back to the AC driver 20. This backlight receiver measures the light intensity generated on the test material so that a check is possible whether it actually corresponds to the desired value.
• a feedback loop is formed by the feedback, so that the light intensity can always be regulated to a predeterminable value.
• FIG. 8 shows an alternative circuit to that of FIG. 7.
• an incandescent lamp 22 is used as the light source.
• the logic circuit LOGIC 18 and the digital-to-analog converter (digital-to-analog converter DAC) 19 feed the incandescent lamp 22 here via a direct current driver (DC driver). 23.
• An additional AC driver 24 processes the signals from LOGIC 18 and digital-to-analog converter (DAC) 19 as well as from a backlight receiver 21 and then feeds a chopper (Shutter) 25.
• a high frequency is generated by means of the chopper in order to generate a light which can be distinguished from the frequencies of the ambient light and can therefore be measured independently of the ambient light.
• the light frequency generated in this way serves as a carrier frequency for the measurement. It must of course be so high that the scanning or resolution is sufficient for the moving test material. With the circuit described it is possible to regulate the light intensity of the light emitted by the incandescent lamp sufficiently quickly and precisely.
• FIG. 9 shows a circuit for processing the current values emitted by the light receiver as a light intensity value by means of adjustable measuring amplifiers.
• the location-dependent course of the intensity of the detected light of each individual optical element of the optoelectronic transducer arrangement can thus be amplified to a programmable setpoint. With this circuit, the light hits a photo receiver
• Photo receiver 26 the electrical signal of which is amplified by a measuring amplifier (variable amplifier) 27.
• the amplifier 27 is controlled by a logic circuit (LOGIC) 28 and a digital-to-analog converter (digital-to-analog converter DAC) 29.
• the logic circuit (LOGIC) 28 is supplied with power via the line 30 and controlled by a line 31, which by a common control channel
• FIG. 10 shows an alternative circuit.
• the photo receiver (photoreceiver) 33 is preceded by a chopper (shutter) 34, which via the logic circuit (LOGIC) 28, the digital-to-analog converter (digital-to-analog converter DAC) 29 and an AC / DC driver (AC / DC Driver) 35 is controlled.
• the chopper enables a selective adjustment to a specific transmitter frequency.
• the measured intensity ' with the help of this chopper be reduced arbitrarily.
• a number of photodiodes, incandescent lamps, gas discharge tubes or lamps can serve as linear light sources on devices according to the invention.
• Semiconductor diodes can also be used.
• the optoelectronic transducer arrangements can consist of photodiodes, phototransistors or photomultipliers.
• Means for moving the light source and the optoelectronic transducer arrangement relative to the test material and for detecting the location coordinate of these movements as parameters for the light source and the optoelectronic transducer arrangement are only required if the test object is stationary. These means can be, for example, linear units or any mechanical drive means from the prior art. In many cases, the test arrangement is stationary and the test material is moved under the light bar generated.
• the temperature can also be a process parameter that is used as a control parameter (reference variable).
• a control parameter reference variable
• red glowing metal can be cited which is used for a measurement. influences, or the temperature of a test specimen must be compensated due to the material expansion.
• infrared pyroelectric sensors are suitable as optoelectronic elements.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Textile Engineering (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Length Measuring Devices By Optical Means (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1990
  • 1990-01-06 CH CH31/90A patent/CH681112A5/de not_active IP Right Cessation
• 1991
  • 1991-01-07 AU AU69118/91A patent/AU6911891A/en not_active Abandoned
  • 1991-01-07 BR BR919103915A patent/BR9103915A/pt not_active IP Right Cessation
  • 1991-01-07 KR KR1019910701040A patent/KR920701784A/ko not_active Withdrawn
  • 1991-01-07 CA CA002050316A patent/CA2050316A1/en not_active Abandoned
  • 1991-01-07 RU SU915001624A patent/RU2058546C1/ru active
  • 1991-01-07 JP JP3501170A patent/JPH04506411A/ja active Pending
  • 1991-01-07 EP EP91900711A patent/EP0462240A1/de not_active Withdrawn
  • 1991-01-07 WO PCT/CH1991/000004 patent/WO1991010891A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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