WO2005066050A1 - Procede et dispositif pour detecter sans contact des objets plats - Google Patents

Procede et dispositif pour detecter sans contact des objets plats Download PDF

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Publication number
WO2005066050A1
WO2005066050A1 PCT/EP2004/014639 EP2004014639W WO2005066050A1 WO 2005066050 A1 WO2005066050 A1 WO 2005066050A1 EP 2004014639 W EP2004014639 W EP 2004014639W WO 2005066050 A1 WO2005066050 A1 WO 2005066050A1
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WIPO (PCT)
Prior art keywords
characteristic
measurement signal
receiver
correction
curve
Prior art date
Application number
PCT/EP2004/014639
Other languages
German (de)
English (en)
Inventor
Dierk Schoen
Original Assignee
Pepperl + Fuchs Gmbh
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from DE102004056742A external-priority patent/DE102004056742A1/de
Application filed by Pepperl + Fuchs Gmbh filed Critical Pepperl + Fuchs Gmbh
Priority to US10/597,028 priority Critical patent/US7726214B2/en
Priority to JP2006548162A priority patent/JP4919809B2/ja
Priority to EP04804233.7A priority patent/EP1701901B1/fr
Publication of WO2005066050A1 publication Critical patent/WO2005066050A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
    • B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
    • B65H7/06—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed
    • B65H7/12—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed responsive to double feed or separation
    • B65H7/125—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed responsive to double feed or separation sensing the double feed or separation without contacting the articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2515/00—Physical entities not provided for in groups B65H2511/00 or B65H2513/00
    • B65H2515/10—Mass, e.g. mass flow rate; Weight; Inertia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
    • B65H2557/20—Calculating means; Controlling methods
    • B65H2557/24—Calculating methods; Mathematic models
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
    • B65H2557/20—Calculating means; Controlling methods
    • B65H2557/24—Calculating methods; Mathematic models
    • B65H2557/242—Calculating methods; Mathematic models involving a particular data profile or curve
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
    • B65H2557/30—Control systems architecture or components, e.g. electronic or pneumatic modules; Details thereof
    • B65H2557/31—Control systems architecture or components, e.g. electronic or pneumatic modules; Details thereof for converting, e.g. A/D converters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2557/00—Means for control not provided for in groups B65H2551/00 - B65H2555/00
    • B65H2557/30—Control systems architecture or components, e.g. electronic or pneumatic modules; Details thereof
    • B65H2557/32—Control systems architecture or components, e.g. electronic or pneumatic modules; Details thereof for modulating frequency or amplitude
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2701/00—Handled material; Storage means
    • B65H2701/10—Handled articles or webs
    • B65H2701/19—Specific article or web
    • B65H2701/192—Labels

Definitions

  • the invention relates to methods for the contactless detection of flat objects according to the preamble of claims 1 and 6 and devices according to the preamble of claims 37 and 41.
  • Methods and devices of this type are e.g. used in the printing industry to determine whether a single sheet or multiple sheets or a missing sheet is present in the printing and manufacturing process for paper, foils or similar flat materials.
  • a single sheet e.g. of a double sheet
  • such a double sheet is normally required to protect the printing press.
  • the normal printing process is changed or interrupted until a single sheet is detected again.
  • these methods and devices are also used in the packaging industry, in which, for example, labels applied to the base or carrier material are counted or checked for the presence or absence of them.
  • Another area of application is the detection of tear threads or tear points, particularly in the case of thin foils used as wrapping, such as cigarette packs.
  • metal-clad papers, flat plastic eyes or foils and sheets can also be detected in manufacturing processes without contact using such methods and devices.
  • the measuring principle used in a generic method and a device when using e.g. Ultrasound and the detection of paper in sheet-like form is based on the fact that the ultrasound wave emitted by the transmitter penetrates the paper and the transmitted portion of the ultrasound wave is received by the receiver as a measurement signal and its amplitude is evaluated. If a multiple or double sheet is present, the receiver has a significantly smaller amplitude than if a single sheet was present.
  • DIN pocket book 118 (edition 2003-06), DIN pocket book 213 (edition 2002-12), DIN pocket book 274 (edition 2003-06), DIN-Taschenbuch 275 (edition 1996-08), or with regard to corrugated cardboard to DIN 55468-1.
  • a device for the detection of single sheets or multiple sheets is known from DE 200 18 193 Ul and EP 1 201 582 A. To detect these arcs, this known device has at least one capacitive sensor and at least one ultrasonic sensor.
  • Another device is known as a capacitive sensor from DE 195 21 129 Cl.
  • This device which is primarily aimed at the contactless detection of labels on a carrier material, works with two capacitor elements and an oscillator influencing them.
  • the dielectric properties ten of the paper or other flat objects therefore influence the oscillating circuit of the oscillator with regard to the frequency, which is evaluated for detection.
  • the disadvantage here is that relatively thin papers can only be detected with difficulty or not at all, just like metal-coated papers. Even very thin foils are difficult to detect due to their small thickness and the dielectric constant, which in some cases differs only slightly from one.
  • DE 203 12 388 U1 Another device of the type mentioned is known from DE 203 12 388 U1.
  • This device which works with ultrasound, determines the presence and strength of the corresponding objects via the transmission and reflection of the radiation.
  • this device also uses reference reflectors, so that the device has a relatively complex structure.
  • DE 297 22 715 U1 discloses an inductively operating device for measuring the thickness of metal sheets, which can consist of non-ferrous metals or ferrous metals.
  • the thickness of the sheets is measured by evaluating the working frequency of a frequency generator or by evaluating its amplitude.
  • a teach-in step is first required, in which a calibration plate is introduced into the measuring space and the working frequency or the amplitude of the frequency generator is set according to a standard thickness curve.
  • This device is also suitable for the detection of sheet thicknesses up to approx. 6 mm. The detection of thin sheets or foils is not very reliable due to the small change in damping.
  • DE 44 03 011 Cl describes a device for separating non-magnetic sheets.
  • a traveling field inductor when a double sheet is present, exerts a force which is provided opposite to the conveying direction of the sheet stack, so that the present double sheet is separated into two sheets.
  • This device is completely unsuitable for non-metallic flat objects or foils.
  • DE 42 33 855 C2 describes a method for checking and recognizing inhomogeneities in sheets. This method works optically and on the basis of a transmission measurement. However, especially when checking paper sheets with regard to single and multiple sheets, there is the problem that, due to the material properties of the sheets, very large fluctuations are caused due to inhomogeneities or the reflection behavior and the fluttering of the sheets. In order to overcome this problem, this document provides for a measurement evaluation using the fuzzy logic rules.
  • This method which is based on the determination of the weight per unit area or the thickness of the materials to be detected, works with pulsed ultrasound waves, with the evaluation of the integration of the phase shift being used in particular for the detection of a double sheet, ie the presence of two overlapping or overlapping bank notes.
  • the field of application of this method is therefore primarily aimed at counting banknotes or comparable papers and foils, taking into account the basis weights of such materials. This method therefore appears unsuitable for use with packaging materials or counting labels.
  • Comparable methods and devices are known in the field of application for the detection or counting of labels.
  • the difference in a label can be seen here first, since it is provided on a base or carrier material as an applied material layer.
  • This layered material behaves towards the outside in terms of opacity, the dielectric, the electromagnetic conductivity or the sound propagation time as a connected piece of material, so that with these detection possibilities there is only a comparably low attenuation, which is, however, still evaluable.
  • DE 199 21 217 AI together with DE 199 27 865 AI and EP 1 067 053 B1 discloses a device for detecting labels or flat objects.
  • This device uses ultrasonic waves with a modulation frequency, with a threshold value being determined during an adjustment process or a teach-in step in order to distinguish between single and multiple bends.
  • the detection can be set on the special flat object in the sense of a label.
  • this teach-in step makes the device more complex and requires longer setting times when changing to another flat object. This shows that a larger range of materials cannot be detected per se, but only in line with the specific individual material.
  • the object of the invention is therefore to design a generic method and a device for the contactless detection of flat objects, which is very flexible and reliable detection of simple, faulty and over a wide range of materials. or multiple sheets with different flat materials on the one hand, in particular with papers, foils, sheets and the like, on the other hand with labels and similarly layered materials, which can be done without a teach-in step and different beams or waves such as optical, acoustic, inductive Type or the like can be used.
  • this object is achieved in the case of methods by the features of claim 1 or claim 6 and in the case of apparatuses. tions solved by the features of claim 37 or claim 41.
  • An essential core idea of the invention can therefore be seen in specifying a correction characteristic curve for the evaluation of the measurement signal over a grammage and basis weight range in order to achieve a target characteristic curve with a largely linear or almost linear course over the intended material range or also one of the papers and similar materials to achieve an ideal characteristic curve for the detection of the single sheet, which enables a clear distinction when analyzing the amplitude of the amplified measurement signal, in particular as compared to a corresponding threshold value for air, as a threshold for a missing sheet or as a threshold value for a double sheet.
  • a further important core idea of the invention is that when the received measurement signal is amplified, the correction characteristic of the corresponding signal amplification is specified statically or dynamically in order to achieve a target characteristic that can be easily evaluated.
  • the invention also takes into account that an immediate conversion of the measurement signal can be carried out as part of an A / D conversion, the digital values obtained in this way being subjected to the measurement signal characteristic curve to the corresponding purely digital correction characteristic curve, so to speak, so to speak, the evaluable target characteristic curve to reach.
  • This principle of using a correction characteristic curve also has the great advantage that different sensor devices, in particular as a barrier or barrier arrangement, for example in the form of a fork, can be used, it being possible advantageously to use ultrasonic sensors, optical, capacitive or inductive sensors, the same method can equally be used for these sensors.
  • the corresponding correction characteristic for papers and the like. Materials are achieved in particular by mirroring the measured value characteristic at the ideal target characteristic for single sheet detection, possibly with a special transformation of the Cartesian coordinate system.
  • the correction characteristic can also be selected inversely or almost inversely to the characteristic of the input voltage U E of the measurement signal. In this way it is possible to achieve a good approximation of a target characteristic curve that runs ideally for single sheet detection over a relatively large grammage or basis weight range of the objects to be detected, in particular between 8 g / m 2 and 4000 g / m 2 . Inverse is seen as an inverse function.
  • the method according to the invention is therefore not only suitable for the detection of single sheets, multiple sheets or missing sheets of thin to thick papers which are in the above-mentioned grammage range. Rather, stackable, box-shaped packaging made of paper or plastic or labels applied to carrier material, or adhesive, tear-off or tear-open points of paper or foils can also be detected.
  • the corresponding correction characteristic which can also consist of a combination of several correction characteristics, is preferably impressed on the output side to obtain an easily evaluable target characteristic curve over the entire basis weight range for further evaluation.
  • the corresponding flat object can then be detected with regard to certain threshold values in a subsequent method step, which can be implemented, for example, in a microprocessor, so that a clear detection signal for single sheets, missing sheets or multiple sheets is obtained.
  • the method also provides that the measurement signal or its measurement signal characteristic curve received in the receiver is subjected directly to an analog-digital conversion, these digital values taking into account a corresponding purely digital correction characteristic curve to a target characteristic curve with generation of a corresponding one Detection signals are processed.
  • the advantage of these measures is that reliable detection of the corresponding flat objects over a very large grammage and basis weight range is achieved without the need for a teach-in process, which would lead to system downtimes.
  • the dynamic range of the evaluation device is expanded considerably, so that the detection of very thin or very inhomogeneous materials, which tend to flutter behavior, can be implemented with good certainty.
  • the method according to the invention therefore makes it possible, on the basis of the amplitude evaluation of the measurement signal received in the receiver, by means of a correction characteristic and target characteristic, to reliably distinguish single sheets, missing sheets and multiple or double sheets, and this for very thin or very sound-transmissive objects, for example with a basis weight of 8 g / m 2 or approx. 10 ⁇ m thickness, up to relatively thick and strongly sound-transmissive objects up to 4000 g / m 2 , e.g. with a thickness of 4 mm, without a prior teach-in process differ.
  • the invention also provides for correction characteristic curves to be taken into account, which represent a combination of different correction characteristic curves, these combined correction characteristic curves also only in sections over partial areas of the entire grammage range can be applied. This makes it possible to achieve the target characteristic curves with improved approximation to the ideal characteristic curve for the detection of single sheets.
  • the correction characteristic can also be used in sections as a linear or non-linear characteristic, as a single or multiple logarithmic characteristic, as an exponential characteristic, as a hyperbolic characteristic, as Polygon course, be designed as a function of any degree or as an empirically determined or calculated characteristic curve or as a combination of several of these characteristic curves.
  • the correction characteristic as an approximately linearly increasing and weighting or exponentially or similarly increasing characteristic or as a logarithmic, multiple-logarithmic or similarly running nonlinear characteristic, also designed in combination with the first mentioned correction characteristics.
  • the basis weight range for labels and similar materials can be set from approximately 40 g / m 2 to approximately 300 g / m 2 , that is to say is relatively narrow.
  • the correction characteristic curve for the detection of labels is therefore preferably at least linear, this linear correction characteristic curve KK having a weighting function, or is chosen to increase exponentially.
  • multi-layered materials, such as labels even with slight changes in grammage, depending on the entire grammage or basis weight range.
  • evaluation is primarily carried out for the presence or absence of, or for multiple layers reduced by at least one layer.
  • the invention also makes it possible to implement such a combination of correction characteristic curves, for example also in separate paths or channels.
  • the logarithmic and / or double logarithmic correction characteristic to be stamped on the first channel, for example, to thereby primarily the double sheet detection • reliably achieved.
  • the second channel can then, for example, be subjected to an exponentially or linearly increasing correction characteristic, in order to optimally implement the detection of labels, glue points or thread detection in this path.
  • This combination of the two opposing methods with a logarithmic correction characteristic in combination with an exponentially increasing correction characteristic therefore creates an optimal detection possibility for labels and materials such as tear or tear points and / or tear threads and simple, faulty - and multiple sheets.
  • a linear signal amplifier can, for example, achieve a voltage-signal ratio on the order of 50: 1, which corresponds to approximately 34 dB.
  • a logarithmic signal amplifier achieves a voltage-signal ratio of 3 ⁇ 10 4 : 1, which corresponds to approximately 90 dB.
  • logarithmic and / or multiple logarithmic signal amplifiers can also be used in the method according to the invention and the corresponding device, so that the possible spectrum of materials is expanded to thin or very light arcs.
  • This is due to the fact that with an increasing signal level in these signal amplifiers, the characteristic of the signal amplification saturates and there is practically no signal swing anymore.
  • With decreasing signal amplification for large signals even with the slightest changes, such as, for example, very thin sheets of paper between the transmitter and receiver, signals that can still be easily evaluated can still be obtained.
  • Another advantage of using nonlinear, in particular logarithmic and / or multiple logarithmic signal amplifiers is that the detectable material spectrum is expanded to thicker or heavier arcs. This results from the fact that with a low signal level the amplification is very high and even the weakest signals, which still penetrate a heavy or thick single sheet, are amplified sufficiently and can be evaluated. This property is used in particular for the detection of stacked packaging or also for the detection of single sheets, missing or multiple sheets.
  • a further expedient development of the invention consists in that the correction characteristic curve is determined or calculated empirically, in particular empirically.
  • the transmission attenuation or the resulting measurement signal voltage can be plotted as a function of the grammage or the basis weight of the object or objects to be detected, and in this way the Characteristic curves of the measurement signal of a plurality of different objects are determined and the optimal inverse or almost inverse correction characteristic curve is arithmetically or empirically generated in order to achieve a target characteristic curve which is at least approximated to the ideal target characteristic curve for the detection of single sheets.
  • a corresponding electrical network for adjusting the correction characteristic e.g. a microprocessor
  • a corresponding electrical network for adjusting the correction characteristic e.g. an application-specific component or a resistance network can be used.
  • the target characteristic for different material spectra is divided into several sections, in particular three sections or five sections.
  • a partial target characteristic curve for the grammage range above 1200 g / m 2 for very thick papers and another section below 20 g / m 2 for a very thin paper spectrum can be formed.
  • the introduction of sections of the target characteristic curve therefore enables improved reliability with regard to single, missing or multiple sheet detection.
  • the amplitude value is compared with threshold values on the basis of the target characteristic. These are in particular an upper threshold for air and a lower threshold for double or multiple sheets.
  • the received measurement signal with the corresponding value of the target characteristic is greater than the upper threshold value, this is evaluated as a "missing sheet".
  • a received measurement signal lower than the lower threshold value means a "multiple or double sheet”. In the case of a received measurement signal with the corresponding value on the target characteristic between the threshold values, this is detected as a "single sheet".
  • the threshold values in particular for multiple sheets, can be designed to be continuously defined or in sections, or can be designed to be dynamic.
  • a dynamic double sheet threshold can be used to further expand the measurable grammages.
  • the single sheet value measured and with the associated multiple sheet value e.g. be evaluated as a polygon function if it is a simple function, e.g. a falling straight line or a constant value for the single arc.
  • the method and the device can be implemented particularly well by means of at least one ultrasound sensor device.
  • the sensor device preferably has at least one pair of coordinated and coaxially aligned ultrasound transducers.
  • the method and device according to the invention can also be used with optical, capacitive or inductive sensors.
  • the operating mode of the sensor device is expediently selectable or switchable as a pulse operation or continuous operation depending on the material spectra to be detected and the operating conditions.
  • the pair of sensors In the case of continuous operation, it is preferable to mount the pair of sensors at an angle to avoid interference or standing waves using this measure.
  • the continuous operation is expediently designed as a quasi-continuous operation, for example by periodically, compared to the evaluation time short periods, the signal is switched off and on again. To avoid standing waves, phase jumps can also be provided in the transmission signal.
  • the inclined mounting of the pair of sensor elements is particularly suitable for the detection of thicker materials, e.g. single-wall or multi-wall, in particular double-wall corrugated cardboard, in order to achieve better material penetration and to avoid interference.
  • the transmission signal has also proven to be advantageous to modulate the transmission signal with at least one modulation frequency.
  • tolerances of the transducers can be corrected or compensated, in particular in the case of ultrasonic sensors.
  • the sensor elements are matched to one another, they generally have different resonance frequencies. If a frequency sweep f s with a frequency significantly lower than the exciting frequency is used for frequency modulation, the resonance maximum of the sensor elements is periodically exceeded. If the response time of the sensor is significantly less than l / f S / , the transducer properties of each individual sensor element or sensor pair can be optimally used for ultrasound transmission in this way.
  • the frequency sweep will normally be up to some 10 kHz.
  • the tolerances of the sensor elements are expediently corrected automatically before or during operation. This is done by normalizing the sensor element pairs to a fixed value at a predetermined fixed distance, in particular the optimal mounting distance. As a result, bad sensor elements are made better and good sensor elements or transducers are made worse. A correction factor is necessary to compensate for this. According to the method, this can be done by using a straight line which is stored or calculated as value pairs in the microprocessor uP, since the measurement signal is already with e.g. a simple logarithmic correction characteristic is evaluated and the correction characteristic generates an approximately linearly falling target characteristic over the transducer or sensor element distance. That the input signal at the microprocessor of an evaluation device drops linearly with the transducer distance to a good approximation.
  • the correction of the values is easy even with a variable distance, since when a corresponding device is switched on, only a straight line function for the correct initial value has to be calculated or stored as a pair of values.
  • the correct determination of the sensor head distance is carried out by a run time measurement.
  • a particular advantage of the method using ultrasound can be seen in the fact that the distance between transmitter and receiver in the sensor device can be configured variably for this teach-in-free method.
  • the sensor device can be adapted to different applications relatively quickly with regard to its distance, without the measuring precision of the method being impaired thereby.
  • a further improvement of the method can be brought about by monitoring the distance between transmitter and receiver and determining it. This determination of the distance between the transmitter and receiver can be realized on the one hand by reflection of the radiation between the transmitter and receiver and on the other hand by means of reflection between see transmitter and receiver despite a flat material in the space in between, even a thick sheet. If it is determined that the permissible maximum sensor distance has been exceeded, the evaluation device, for example a microprocessor, can carry out a corresponding correction of the determined amplitude values of the measurement signal depending on the distance between the transmitter and receiver.
  • the transmitter and receiver are aligned with one another in the main radiation direction, in particular coaxially, with one another, with almost any angle of inclination to the plane of the arc being able to be provided.
  • a method can also be used to provide feedback between the transmitter and the evaluation device, in particular a microprocessor, in order to obtain a maximum amplitude at the output, taking into account the material specification of the flat objects to be examined and other operating conditions. It is also possible to regulate the optimum transmission frequency. With this measure, aging effects of the sensor elements can also be compensated for and a product test of the device according to the invention, in a particularly advantageous embodiment of the invention, can be fully automated during series production.
  • these objects can be moved between the transmitter and receiver so that, depending on the specific measurement signal of the object received, the corresponding switching threshold for the object is automatically or externally triggered Target characteristic is determinable.
  • a feedback is provided between the evaluation device and the transmitter, by means of which the amplitude of the received measurement signal can be maximized. It is also preferred to provide a self-alignment between transmitter and receiver with regard to an optimal transmission frequency and / or amplitude. This self-adjustment can be carried out in times synchronized with the transmission frequency, in defined pause times or also via a separate input provided externally on the sensor device.
  • the activation and selection of the corresponding channels and signals is preferably carried out via time-division multiplexing devices.
  • the diaphragms, and in particular the slit diaphragms in particular, are arranged in the thread running direction to improve the detection of material threads adhering to a base or carrier material, for example tear threads in packaging foils for cigarettes. This is usually an arrangement of the diaphragm for the direction of travel of the elongated objects.
  • slit or perforated diaphragms are aligned by 90 ° to the direction of movement of the sheets.
  • the elongated object guided between the transmitter, receiver and diaphragm e.g. a thread laminated onto a carrier material, hovering as close as possible over the screen or slidingly touching it.
  • the arrangement of the transmitter especially in the case of ultrasound sensors, is advantageously carried out below the sheet to be detected, since in this case the maximum transmission energy can be coupled out and self-cleaning effects on the sensor head can be used.
  • Fig. 1 shows the principle of a method according to the invention and block-like a corresponding device including voltage diagrams according to Figures la, lb, lc, which illustrate the structure of the characteristic curves in the detection of sheets of paper, foils or similar materials.
  • FIG. 2 shows the principle of a method according to the invention and a corresponding device in block diagram form, including voltage diagrams according to FIGS. 2a, 2b, 2c, 2d, which illustrate the structure of the characteristic curves in the detection of labels, tear-open points and similar materials;
  • 3a shows a curve diagram which shows the schematic dependency of the output voltage of an amplifier, as shown in FIG. 1 by way of example, as a function of the grammage or the basis weight of the tectating materials, including idealized target characteristics;
  • Fig. 3b is a schematic diagram analogous to Fig. 3a with the output voltage of an amplifier as a function of the grammage or the basis weight of the materials to be examined, with several target characteristics together with corresponding threshold values, e.g. Air threshold, double arch threshold are shown;
  • threshold values e.g. Air threshold, double arch threshold are shown;
  • 4a shows a schematic representation of how the correction characteristic curve can be determined in the Cartesian coordinate system in the case of a known measured value characteristic curve and ideal target characteristic curve for single or double sheet detection;
  • 4b shows a schematic illustration, based on the label recognition with ideal target characteristic curve, known measured value characteristic curve and a correction characteristic curve required for transformation
  • Fig. 4c is a schematic representation of the characteristics
  • 4d shows characteristic curves for double sheet detection with reflection on an imaginary axis, including the transformation according to FIG. 4f;
  • 4e shows a schematic illustration of characteristic curves for label recognition with reflection on the imaginary axis, taking into account FIG. 4f; 4f schematically shows a transformation of the Cartesian coordinate system by an angle ⁇ with a reference axis of the new ' coordinate system;
  • 4g shows a schematic representation of the ideal target characteristic and real drawing characteristics in double sheet detection
  • 4h shows a schematic representation of an ideal target characteristic and a realistic target characteristic for label recognition
  • 4j shows a schematic representation of a measured value characteristic derived from a weighted hyperbola and a correction characteristic derived from a logarithmic function with the target characteristic determined therefrom for single or double sheet detection;
  • 5a is a schematic illustration of the principle of the measurement criteria present as an example in the detection of a double sheet of material by means of ultrasound waves;
  • FIG. 5b in a manner comparable to that in FIG. 5a, the schematic representation of an adhesive point between a double sheet of material and the measurement criteria that arise in this case when recorded by means of ultrasound;
  • 5c shows the schematic representation of materials adhered to a base or carrier material, partly as single-layered and partly as multi-layered materials, this structure showing the structure of a label;
  • FIG. 6 shows the method and a device in the form of a block diagram using the example of a combination of different correction characteristic curves
  • FIG. 7 shows a schematic illustration similar to FIG. 6, the principle for setting a correction characteristic curve and calculating a correction characteristic curve with feedback on the circuit blocks being illustrated;
  • Fig. 9 is a schematic block diagram representation of a method or the corresponding device with the combination e.g. the multiple sheet detection with the detection of material layers or labels adhered to the carrier material;
  • FIGS. 12a and 12b the arrangement of a sensor with optimal alignment in a single-wall corrugated cardboard and corresponding to FIG. 12b, the analog alignment of a sensor with corrugated cardboard.
  • the diagram according to FIG. 1 schematically shows the method according to the invention and a device with a block-type structure and the voltage curves that can be achieved at certain points in the sense of characteristic curves over a grammage or basis weight range g / m 2 of a material spectrum to be detected.
  • a corresponding sensor device 10 in this case has on the one hand a transmitter T and an opposing receiver R aligned therewith, between which the flat objects to be detected, in the example in the form of an arc, are moved without contact.
  • a multiple sheet as double sheet 2 is shown as an example.
  • a possible voltage curve U M is dependent on the grammage or the basis weight g / m 2 for the measurement characteristic MK shown in FIG.
  • threshold values such as for the air threshold or as a double sheet threshold, to unambiguously intersect with these threshold values or as large a voltage gap as possible to get these thresholds.
  • the principle according to the invention is therefore to take into account a correction characteristic and e.g. to impress the evaluation circuit following the receiver, for which purpose the following amplifier device is particularly suitable in order to achieve a target characteristic which can be easily evaluated over the desired grammage range for reliable detection by deciding whether a single sheet, no sheet or a multiple, in particular double sheet, is present.
  • Such a correction characteristic KK is shown schematically in FIG. 1b.
  • This correction characteristic curve which only shows in principle the dependence between the output voltage U A and the input voltage U E in FIG. 1b, illustrates in comparison with the measurement characteristic curve MK according to FIG. 1 a, which likewise only shows the course of the measurement signal U M only schematically shows that relatively high voltage values U M seen over the grammage range experience no or only a slight gain, while smaller voltage values, for example with relatively large basis weights (g / m 2 ), experience a significantly higher, possibly exponential gain.
  • the resulting target characteristic curve ZK with the voltage U z as a function of the grammage (g / m 2 ) is also only shown schematically in FIG. 1c.
  • the desired ZK can also be transformed from a point-by-point mapping (implicit KK) of the measurement signal U M to the desired output signal U z and thus the desired target characteristic ZK can be achieved.
  • a variable gain amplifier is necessary ⁇ which then receives the correction characteristic of a uP.
  • mapping of the measurement signal U M to the desired output signal U z on the basis of the KK can also be done point-by-point instead of value-discretely, also continuously.
  • This target characteristic curve shown in FIG. 1 c could have, for example, the curve shown by the solid line, which has three areas. A first and a third relatively steeply sloping area and a middle area, which is inclined only relatively slightly to the abscissa and which comprises a large grammage area.
  • a linearly decreasing target characteristic ZK2 going through the end points of the first target characteristic ZK1 is shown with an interrupted line as an improved target characteristic.
  • the measurement signal U M received at the receiver R. is fed to an evaluation device 4.
  • the evaluation device 4 is shown in a simplified manner with the amplifier device 5 and downstream of a microprocessor 6.
  • the correction characteristic KK is specified or impressed in the amplifier device 5, so that the target characteristic ZK1 or ZK2 is obtained at the output for further evaluation in the microprocessor 6.
  • the microprocessor 6- can then generate a corresponding detection signal with regard to single sheets, missing sheets or multiple sheets, in particular double sheets, taking into account stored or dynamically calculated data, such as threshold values.
  • FIGS. 2a, 2b, 2c, 2d schematically show the method and a device for the detection of labels and similar materials without a teach-in step having to be carried out.
  • the reference symbols here correspond to the reference symbols from FIG. 1.
  • the block-type structure shows a transmitter T, e.g. for the emission of ultrasonic waves, and an assigned receiver R as a sensor device 10. Labels 7 are passed through between the transmitter T and the receiver R.
  • the aim of the device is therefore on the one hand to recognize whether labels or no labels are present. On the other hand, it is also possible to determine the number of labels passed through the sensor device.
  • the measurement signal U M or U E obtained when a label is present in the receiver R can, for example, have the schematically indicated curve of the characteristic curve over the grammage, with a curve that drops approximately linearly, non-linearly, exponentially or the like.
  • the following evaluation device which e.g. can have an amplifier device 5 and a microprocessor 6 connected downstream, receives a correction characteristic in the amplifier 5, which e.g. linearly increasing (I.) or exponentially increasing (II.) as shown in FIG. 2b.
  • a correction characteristic in the amplifier 5, which e.g. linearly increasing (I.) or exponentially increasing (II.) as shown in FIG. 2b.
  • the correction characteristic e.g. a target characteristic over the grammage range as shown in FIG. 2c by the curve shape I or II.
  • This target characteristic ZKi has the course of a negative falling straight line, from smaller grammages to larger grammages, optimally a constant slope and a maximum voltage difference for the output voltage U z small differences in grammage should be achieved over the entire grammage or basis weight range intended for the detection of labels.
  • correction characteristic curve KK can also be a combination of individual different characteristic curves.
  • Other correction characteristic curves such as logarithmic or multiple logarithmic, can also be used depending on the characteristic curve profile of the measurement signal U M and the gain characteristic curve.
  • the aim here is to achieve an ideal characteristic curve ZKi, as shown in FIG. 2, if possible.
  • the curve profiles according to FIGS. 2a, 2b, 2c show two examples of different characteristic curves.
  • the measurement signal U M according to FIG. 2a with the characteristic curve MK of a first characteristic I and a characteristic II with an interrupted line.
  • the output voltage U A of an amplifier device over the grammage range is shown in a schematic representation in FIG. 2 d with an exemplary course of a measured value characteristic MK E for a label and the target characteristic ZK E , as is taken into account with a correction impressed on the amplifier.
  • Characteristic curve KK can be reached. The illustration applies to the recognition of labels or glue points.
  • the measured value characteristic MK E is transformed by means of a suitable correction characteristic KK.
  • every point of the measured value characteristic MK E is transformed continuously or value-discretely in digital systems into a corresponding value on the target characteristic ZK E mized. This is illustrated by the arrows for clarification.
  • the amplifier voltage can very easily be in the saturation range.
  • the use of foils for labels can also quickly reach the limit range of the amplifier for noise, since foils vaporize very strongly.
  • the method of characteristic curve correction can be used particularly advantageously in the case of such measurement value characteristic curves MK E , so that saturation of the measurement signal is avoided in the case of very thin and strongly damping materials, which ultimately ensures flawless detection of the presence or absence of labels.
  • a possible course of the measured value characteristic MK DB for a single sheet for double sheet detection of preferably paper materials is shown as an example, which approaches the double sheet threshold DBS approximately asymptotically in the upper grammage range.
  • FIG. 3a shows a schematic representation of the basic dependency of a standardized output voltage signal U A / pu of a signal amplifier as a function of the basis weight or the grammage (g / m 2 ) in the case of differently designed signal amplifiers for single and multiple sheets, especially double sheets.
  • the line I in FIG. 3a symbolizes a largely idealized course in the output voltage of single sheets as a function of the grammage when using an approximately linear signal amplifier 5, with an approximately exponential drop in the voltage line.
  • This voltage characteristic I does not take into account any correction characteristic KK. From this approximately exponentially decreasing voltage characteristic curve I, by using the nonlinear, in particular logarithmic and / or double logarithmic correction characteristic curve KK inherent or impressed in the corresponding signal amplifier, a desired target characteristic curve II for single sheets over a ' very large grammage range, that is to say various materials.
  • the target characteristic curve II thus symbolizes a characteristic curve for the output signal in the case of single arcs when using a logarithmic signal amplifier, the target characteristic curve II exhibiting an approximately linear drop.
  • the air threshold and, on the other hand, the double arc threshold are entered as examples in the diagram according to FIG. 3a.
  • the intersection points of the target characteristic curve II according to FIG. 3a with the air threshold or the double arch threshold show a sufficiently high steepness around a defined, relatively small material area.
  • This ideal target characteristic is marked I in Fig. 3b. 3a also shows a curve la which shows a multiple-arc signal, in particular a double-arc signal when using an approximately linear signal amplifier, the curve la having an approximately double-exponential drop in the multiple-curve characteristic.
  • the curve Ila further exemplified symbolizes a multiple sheet signal, in particular a double sheet signal, with logarithmic correction characteristic, whereby propositionungswei- ⁇ se a simple exponential decay of Mehrfachbogen- characteristic Ila is achieved.
  • 3b shows several target characteristic curves of single sheets with the representation of the standardized output voltage U A / pu of the signal amplifier as a function of the grammage or the basis weight (g / m 2 ) when using different signal amplifiers.
  • the top horizontal line with a broken line marks the saturation limit or maximum supply voltage for a signal amplifier used.
  • the threshold value for air or a missing sheet is shown as an example at about 0.7 U A / pu. At a value of U A of approximately 0.125, the double arc threshold and, below that, the threshold for the noise of electrical signal amplifiers are shown as examples.
  • the horizontal line I in Fig. 3b indicates an ideal target characteristic for single sheets.
  • This ideal target characteristic shows no saturation for thin materials and is at a high distance from the noise threshold or the double-arc threshold.
  • This ideal target characteristic curve means that the output voltage U A of the signal amplification would ideally result in a constant signal if a wide variety of grammages or grammages were entered.
  • Curve II shows a non-linear target characteristic with two branches Ila and Ilb, which is relatively difficult to implement due to the turning point, but can be regarded as a characteristic approximating the ideal target characteristic I for single sheets.
  • the relatively flat partial areas of Ila and Ilb could be realized, the area Ila for lighter grammages advantageously being able to be realized via an almost linear signal amplification.
  • the area Ilb for heavier grammages can e.g. can be realized by means of a double logarithmic signal amplification, the steeply falling kink proving to be too complex in technical implementation due to the damping properties of papers with a very high grammage.
  • Curve III represents a target characteristic curve which approximates the end points of curve II in the simplest way by means of a 2-point straight line connection to an ideal course as shown in curve I.
  • This can be achieved by using a minimum of simple logarithmic signal amplifiers and shows the linearization of the measured values for single sheets over a large grammage range taking into account a corresponding correction characteristic.
  • the curve III has clear passages for the threshold values for air or for a double sheet, so that clear shift points and detection criteria are present in 'relation to these thresholds.
  • Target characteristic curves according to curves I, II and III therefore allow unambiguous detections over a material spectrum that is broadened compared to the prior art.
  • Curve IV which is also shown, shows an unsuitable target characteristic for single sheets.
  • an asymptotic course of curve IV to the saturation limit in the upper area and on the other hand to the threshold value of the noise in the lower area.
  • Such an asymptotic course should also be avoided with respect to the switching thresholds for air or for double arcs, since a clear distinction of the states, missing arcs or double arcs, would then be problematic because of the small signal differences to these thresholds.
  • the target characteristic curve is to allow unambiguous detection for single sheets, missing sheets or double sheets over a very large material spectrum, a course according to curve IV should be avoided.
  • FIGS. 1, 2, 3a and 3b therefore show that when evaluating the received measurement signal, a signal amplification is used, which is given a correction characteristic curve, which is the characteristic curve of the output voltage U A / pu depending on the Grammage of the flat objects over a large grammage range inversely or almost inversely or the target characteristic curve approximated to the ideal characteristic curve for single sheet detection in a suitable manner.
  • a linear or almost linear dependency is achieved between the measurement signal U E received by the receiver and the signal voltage U A at the output of the signal amplifier.
  • FIG. 4a schematically shows in the Cartesian coordinate system with the material spectrum g / m 2 on the abscissa and the percentage signal output voltage U A on the ordinate an exemplary course of a measured value characteristic MK DB for the detection of single or double sheets.
  • the required correction characteristic KK DB is also shown for this example. From this it can be seen that first the points of the measured value characteristic MK are transformed in the direction of the arrows P downward and then for larger grammages a transformation upward in order to achieve the ideal target characteristic ZKi for single sheet detection.
  • the example according to FIG. B shows corresponding courses of the characteristic curves for labels.
  • the measured value characteristic MK E is shown as an example with a solid line.
  • the ideal target characteristic ZK E represents a straight line with a negative slope or high stroke.
  • the correction characteristic KK E required for the transformation is shown with an interrupted line and in this case has a point of discontinuity at the intersection between the measured value characteristic MK E and the target characteristic ZK E.
  • FIG. 4c schematically shows the course of the characteristic curves for single or double sheet detection for a case in which not the ideal target characteristic, but a real target characteristic ZK DBr is achieved.
  • the real target characteristic ZK DBr therefore has a stroke H DBr that is greater than 0.
  • the drawn-in measured value characteristic curve MK DB could be transformed into the target characteristic curve ZK DBr by impressing, for example, the correction characteristic curve KK DB as an upper, continuous line. This transformation is indicated by the arrows P.
  • the diagram according to FIG. 4d schematically shows the transformation of a measured value characteristic MK DB for single or double sheet detection to the desired target characteristic ZK DB .
  • the abscissa marks the material spectrum g / m 2 , the realistic measuring range M DBr being indicated.
  • the signal output voltage U A of the measured value is indicated as a percentage on the ordinate. This corresponds approximately to the attenuation measure dB. Furthermore, the virtual endpoints El and E2 as shown ge 'covered intersections of the measuring value characteristic MK DB with the target characteristic ZK DB.
  • measuring value characteristic MK DB in the double sheet detection of a linear target characteristic ZK DB is a correction characteristic KK DB necessary to achieve, as in broken line between the end points El and E2 shown.
  • the measured value characteristic MK DB is transformed in the direction of the arrows to the real target characteristic ZK DB . This is achieved, so to speak, by mirroring the measured value characteristic MK DB on the ZK DB axis after coordinate transformation.
  • FIG. 4e schematically shows the transformation of the measured value characteristic MK E for labels into the desired, ideal target characteristic ZK E by means of the required correction characteristic KK E.
  • the correction characteristic KK E can be achieved by mirroring MK E on the axis of the target characteristic ZK E after the coordinate transformation (see FIG. 4f).
  • the coordinate transformation shown in FIG. 4f shows, in a simplified manner, the shift for a rectilinear coordinate system x, y by an angle ⁇ .
  • X, y are, for example, the axes of the Cartesian rectilinear coordinate system.
  • the new coordinate reference system is specified by the imaginary reference axis of the target characteristic curves ZK DB or ZK E through the coordinate transformation.
  • the arrow in the diagram indicates the transition from the ideal target characteristic ZKi to real target characteristics, e.g. ZK X or ZK 2 .
  • the ideal target characteristic ZKi for label recognition has a maximum stroke Hi over a relatively large range of the material spectrum, which is characterized as the ideal material spectrum Mi.
  • Real target characteristics ZK X in label recognition deviate from the ideal target characteristic ZKi in the direction of the arrow read off. Accordingly, the more realistic target characteristic ZK X has a smaller stroke Hi and also a smaller material spectrum Mi.
  • 4i and 4j exemplarily show measured value characteristic curves and correction characteristic curves and target characteristic curves derived therefrom.
  • the correction characteristic KK has the function
  • the target curves ZK 3 shown . and ZK 2 can therefore be derived from the measured value characteristic MK and the correction characteristic KK essentially by the difference.
  • the example according to FIG. 4j also schematically shows characteristic curves for single or double sheet detection.
  • the measured value characteristic curve MK is approximately derived from a weighted hyperbola.
  • the correction characteristic KK is a correction characteristic derived from a logarithmic function.
  • the measured value characteristic MK can be transformed into a target characteristic ZK, taking into account the correction characteristic KK, which approximately corresponds to an ideal target characteristic for single or double sheet detection.
  • Fig. 5a the overlap of two single sheet is schematically illustrated, so that spoken in the overlap region by a double sheet 11 '.
  • This double sheet 11 is to consist of two sheets of paper, the space between the two single sheets being a medium different from their material. Since non-contact detection is provided, it can be assumed that air with parameter Z 0 is available on both sides of the double sheet and that the intermediate medium in the overlap area of the single sheets is air with Z 0 , which is an air cushion due to the surface roughness of the materials is present in this double sheet.
  • the direction of action of the measuring method e.g. by means of ultrasound, is perpendicular to the double sheet region in the example, so that a transmitted ultrasound signal in such a "real double sheet" becomes very small due to the multiple refraction over at least three interfaces, i.e. the transmission factor ideally approaches zero over three layers.
  • a double sheet or multiple sheet can therefore be regarded as a material structure which has a sheet stratification or a box stratification and in one of the spaces between the sheet stratification there is at least one medium, in particular air, which differs from the different sheet materials and which is related to the sheet materials has a clearly different acoustic resistance in the case of an ultrasound measurement method and thus leads to signal reflections.
  • the signal attenuation due to signal refraction and reflection is so great that the emitted signal is disproportionately damped.
  • Such a double sheet also includes a connection of sheets that is not designed to be adhesive, e.g. by means of mechanical gearing or knurling of arches, since the corresponding intermediate medium would also be air. This consideration also applies to multiple sheets in which three or more individual layers of sheet materials are stacked on top of one another.
  • a double sheet 12 with adhesive 13 is shown schematically.
  • the point of glue is considered to be blunt, more or less overlapping or such connections of sheets, in particular sheets of paper, plastics, foils and fabrics (nonwovens).
  • the connection takes place predominantly by means of at least one partial or full surface adhesive medium, in particular by means of adhesive and adhesive strips or adhesive provided on one or two sides.
  • an adhesive point for a method using ultrasound means an "acoustic short circuit" through which the space between the upper sheet Zi and lower sheet Z 2 fills and intimately connects the adhesive material layer, air above and below the single sheet being assumed to be Z 0 becomes.
  • a glue spot could therefore be detected in the detection method using ultrasound essentially as a single sheet with a high grammage.
  • 5c schematically shows two embodiments of labels 15, 17.
  • label is understood to mean at least one or more layers of material or layers of material adhering to a base or carrier material.
  • the layered material behaves e.g. with respect to the sound transmission to the outside like a connected piece of material, so that there is sometimes no significant damping of the respective physical quantities, but only a comparatively low, but still evaluable damping.
  • Possible inhomogeneities in the carrier material or applied material are not taken into account in this consideration, since a faultless material can be assumed in particular for labels.
  • label 15 has an upper material with the parameter Z 2 applied to a carrier material by means of an intimate adhesive connection. There is air with parameter Z 0 on both sides of the label.
  • this intimate adhesive connection there is an acoustic short circuit between the materials in a detection method by means of ultrasound, so that there is an analogy to glue points according to FIG. 5b.
  • FIG. 6 schematically and in block-like fashion shows a device for missing, single and multiple sheet detection, the correction characteristic being generated as a combination of individual characteristics.
  • the flat materials or sheets to be detected are guided between the transmitter T and the receiver R.
  • the correction characteristic curve resulting after the amplifiers is implemented in the example with a first correction characteristic curve in the amplifier device 21 and at least one second correction characteristic curve in the amplifier device 22, which is connected in parallel.
  • the measurement signal present at the output of the receiver R or its characteristic curve over the grammage is therefore subjected to a combined correction characteristic curve in order to obtain an easily evaluable target characteristic curve 23 which is further evaluated in a microprocessor 6.
  • correction characteristic curve can therefore be implemented in a wide variety of ways, since the essential basic idea of the invention is to carry out a detection of single sheets, missing sheets or multiple sheets, and this over a large grammage range without having to integrate a teach-in process ,
  • FIG. 7 shows the schematic and block-circuit-like structure of a modified device for realizing the invention.
  • the measurement signal of the receiver R is subsequently passed to an amplifier device 24, the signal output of which is directed to a microprocessor 6.
  • the microprocessor 6 allows a predetermined correction characteristic to be set via the symbolized potentiometer 25 via the feedback in the path A.
  • a corresponding correction characteristic curve is calculated by means of the microprocessor 6 and the data received or stored, and is fed back and impressed via the path B to the amplifier device 24.
  • the determined correction characteristic curve C can be impressed discreetly or continuously over the path B of the amplifier device 24 or the evaluation of the amplified output signal can be carried out directly in the microprocessor 6 on the basis of the correction characteristic curve C.
  • the empirical determination of a measurement signal characteristic is shown in a schematic representation in FIG. 8.
  • a large number of materials customary on the market are passed between the transmitter T and the receiver R and the corresponding measurement signal characteristic curve is determined.
  • the measuring range will be determined by introducing the thinnest sheet material A available and the thickest sheet material B to be detected.
  • the measurement signal characteristic curve determined in this way can then be sent to the further processing system, e.g. a microprocessor, in order to determine a largely optimal correction characteristic curve for this measurement signal characteristic curve in order to achieve the required target characteristic curve.
  • the further processing system e.g. a microprocessor
  • FIG. 9 an apparatus according to the invention is schematically 40 for insectsrungsurban detection of multiple sheets A, without the • implementation of a teach-in step and the detecting on a carrier material adhesively applied layers of material B, as labels shown.
  • An important idea here is to route the measurement signal evaluation for multiple sheets to a separate channel A with the corresponding correction characteristic curve and, in parallel, the measurement Feed signal evaluation for labels B to a separate channel B with an adjusted correction characteristic.
  • the measurement signal obtained at the output of the receiver R is therefore switched to the corresponding channel A or channel B via a multiplexer 34 controlled by the microprocessor 6.
  • the signal amplification in channel A is subject to a separate correction characteristic with an optimal design for multiple sheet detection.
  • the signal amplification in channel B is subject to a correction characteristic for the label measurement signal.
  • Both channels A, B are fed via a subsequent multiplexer 35, which is also microprocessor-controlled, to the downstream microprocessor 6 for further evaluation and detection of multiple sheets or labels.
  • This device 40 is suitable both for the detection by means of ultrasonic waves.
  • the main advantage is the targeted possibility of including the most suitable correction characteristic curves for the fundamentally different measuring tasks, namely for the most diverse types of material, such as multiple sheets and labels, for evaluation.
  • FIG. 10 schematically shows a diagram of the normalized output voltage U A in% as a function of the grammage.
  • the target characteristic curve 42 of a single sheet is entered with logarithmic amplification over the grammage range.
  • the air threshold LS is shown in the upper area with a solid line and the double arch threshold DBS in the lower area with a broken line.
  • the double-arch threshold can be provided dynamically, and this can take place constantly over sections of the grammage range. This is illustrated by the lines B1, B2 and B3.
  • the dynamic setting of the double arc threshold can also be adjusted linearly or as a polynomial train of any degree, as is shown, for example, between points P1, P2, P3 and P4.
  • this dynamic setting of the double-arch threshold an additional expansion of the measurable grammages or basis weights can be achieved, so that the detectable range of materials can be enlarged even further.
  • FIG. 11 relates to a diagram which is largely similar to that of FIG. 10, the course of the target characteristic curve 42 for the single sheet largely coinciding over the entire grammage range.
  • the dynamic threshold MBS for the multiple sheet and its course between the points Pia, P2a and P3a are shown on the one hand.
  • the curve 44 here marks the upper value of the flutter area for a single sheet and the curve 45 the lower value of the flutter area for a single sheet.
  • FIGS. 12a, 12b schematically show the basic arrangement for the detection of single-wall corrugated cardboard 51 or double-wall corrugated cardboard 60 and the running direction L, taking into account two sensors 61, 62, in particular ultrasonic sensors.
  • the corrugated cardboard 51 according to FIG. 12a is single-corrugated and has at its adhesion points with a lower bottom layer 52 or an upper cover layer 53 adhesive areas 54 and webs connecting the bottom and top layers, which span a corrugated surface 55.
  • These webs 55 between the cardboard shaft and the corresponding, e.g. horizontally running floor or top layers represent, so to speak, an "acoustic short circuit" when using ultrasound.
  • the sensor used in the example according to FIG. 12a has on the one hand the transmitter T and the receiver R, which are aligned coaxially to one another in their main axis.
  • the alignment of transmitter T and receiver R is preferably carried out wa perpendicular to the largest corrugated surface 55 or at an angle ⁇ i to the perpendicular of the single-corrugated cardboard.
  • the angle ß 2 also indicated marks the angle between the perpendicular to the corrugated cardboard and the surface direction of the main surface of the shaft.
  • the optimum angle J3 ⁇ for sound coupling in an ultrasonic sensor onto a single-wall corrugated cardboard, which has a required acoustic short circuit AK between bottom layer 52 and top layer 53, is determined by the slope t / 2h.
  • t is the distance between two wave crests
  • h is the height of the wave or the distance between the bottom layer and the top layer.
  • angles ß 1 and ß 2 are not necessarily necessary for the detection of incorrect, single or multiple layers of corrugated cardboard.
  • FIG. 12b shows a two-ply corrugated cardboard 60 with the lower first shaft 58 and the upper second shaft 59;
  • the arrangement of an ultrasonic sensor T, R corresponds to that according to FIG. 12a.
  • the acoustic short circuit AK1 and AK2 between the individual layers is essential for detection in the case of double-walled or multi-walled corrugated cardboard, ie a material connection in the sense of a web adhering to the layers for connecting the individual cover layers.
  • a material connection in the sense of a web adhering to the layers for connecting the individual cover layers.
  • the method and device provides a solution for the reliable detection of single sheets, false sheets and multiple sheets, especially double sheets, this not only applying over a very wide grammage and basis weight range, but also with regard to flexible possible uses and different material spectra.

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Abstract

L'invention concerne un procédé et un dispositif pour détecter sans contact des objets plats, en particulier de forme courbe, tels que du papier, des films, des plaques, des étiquettes, des collures, des parties détachables, des fils d'ouverture et d'autres matériaux plats ou d'autres emballages. Les procédés et les dispositifs de l'invention comprennent, par exemple dans l'industrie de l'imprimerie, la condition préalable d'atteindre une reconnaissance sûre et précise de courbes simples, de courbes manquantes, de courbes multiples, des doubles courbes particulières, des objets plats, ainsi qu'une reconnaissance des étiquettes. L'invention permet de créer une solution très flexible, opérationnelle par l'intermédiaire d'une très grand rapport de la masse au mètre carré ou le grammage, ce dernier permettant de déterminer une linge directrice de correction du dispositif d'évaluation du dispositif de détection utilisé par le récepteur, la ligne directrice de la tension d'entrée du signal de mesure dans le récepteur étant considérée comme ligne de visée, en fonction du grammage ou de la masse au mètre carré des objets plats, de sorte qu'une dépendance linéaire ou quasiment linéaire ou une ligne directrice idéale est atteinte, cette dernière permettant de reconnaître la courbe de la ligne directrice de la courbe simple comme ligne de visée.
PCT/EP2004/014639 2004-01-07 2004-12-22 Procede et dispositif pour detecter sans contact des objets plats WO2005066050A1 (fr)

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US10/597,028 US7726214B2 (en) 2004-01-07 2004-12-22 Method and device for the contactless detection of flat objects
JP2006548162A JP4919809B2 (ja) 2004-01-07 2004-12-22 平面物体の非接触検出のための方法およびデバイス
EP04804233.7A EP1701901B1 (fr) 2004-01-07 2004-12-22 Procede et dispositif pour detecter sans contact des objets plats

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DE20312388U1 (de) * 2003-03-23 2003-11-20 Pepperl & Fuchs Vorrichtung zur berührungslosen Detektion von Unregelmäßigkeiten der Dicke von flächigen Objekten, wie Papier, Pappe, Folien, Bleche oder Etiketten

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DE102008023185A1 (de) * 2008-05-10 2009-11-19 Leuze Electronic Gmbh + Co. Kg Ultraschallsensor
DE102008023185B4 (de) * 2008-05-10 2016-04-21 Leuze Electronic Gmbh + Co. Kg Ultraschallsensor

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