Compensation for the effects of substrate alloys

Abstract

A method is described for compensating for substrate variations in a measurement of a quantity of a material disposed on a substrate, the method including receiving detected X-ray signals for measurement of the material at a position on a surface of the substrate, and determining a quantity of material based on the received X-ray measurement signals and a predetermined set of compensation parameters for the substrate, the set of compensation parameters varying with position on the surface of the substrate.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority from U.S. Patent Application No. 63 / 269,852, filed on 24 March 2023, which is incorporated herein by reference in its entirety.

[0002] (Field of invention) This disclosure relates to a method for compensating for substrate fluctuations in X-ray measurements of the material quantity of a material placed on a substrate, a method for determining compensation parameters for substrate fluctuations in X-ray measurements of the material quantity of a material placed on a substrate, and an X-ray analysis system. [Background technology]

[0003] X-ray scattering analysis and X-ray fluorescence (XRF) analysis are used in various non-contact industrial process measurements, particularly for thickness measurement. For example, these techniques can be used to monitor the thickness of materials such as webs and coatings applied to webs being transported on a conveyor roll machine. The roll machine may have a surface coating, and the measurement may be based on the assumption that this surface coating is uniform across the entire surface of the roll machine.

[0004] Referring to Figure 1, an exemplary X-ray sensor head configuration for a web measurement process is shown. The apparatus comprises a roll machine 10 and an X-ray sensor head 20. The X-ray sensor head 20 emits X-rays directed at a material such as a web passing over the roll machine 10 and detects the returned scattered or fluorescent X-rays as a voltage signal. As the thickness of the material increases, the scattered radiation and X-ray fluorescence are modulated, such as increasing or decreasing.

[0005] During processing, the roll machine 10 rotates, and the sensor 20 moves along the width (x) of the roll machine, thereby the detected voltage signal is a function of the cylindrical coordinates (x,φ) of the roll machine and time (t). The detected voltage signal can then be correlated to the thickness or basis weight of the material, such as a web or coated web, by linearizing it according to a calibration curve. The voltage signal can also be compensated for temperature before any correlation based on the calibration curve is performed.

[0006] As industrial processing advances, maintaining and improving the accuracy of such measurements becomes a crucial challenge. [Overview of the project]

[0007] This disclosure stems from a new understanding that the surface coating of a substrate (e.g., a conveyor roll machine) that provides a surface on which a material measured by X-ray analysis is placed can be damaged. Typically, the substrate may be repaired using a multi-component filler material (often different from the surface coating of the roll machine). Such repairs may be required in industrial processes.

[0008] It was previously expected that the substrate surface during X-ray analysis would be smooth and have a uniform coating across the entire surface. However, it has been found that additional filler materials can affect detected X-ray signals, such as XRF or X-ray scattering signals, leading to measurement inaccuracies. Filler materials may, for example, absorb or provide additional XRF signals, thereby altering the spectrum. Alternatively, filler materials may cause more or less X-ray scattering, which can alter the X-ray signal. In one embodiment, the present disclosure provides a technique for compensating for this inaccuracy.

[0009] Compensation is achieved by identifying a set of compensation parameters for the substrate surface. These parameters are position-dependent (i.e., they change depending on the position on the substrate surface being measured). Since measurements are performed at multiple locations on the substrate surface, the set of compensation parameters generally covers multiple locations. The parameters are applied in a process of correlating (linearizing) the detected X-ray signal to material quantities, such as thickness, basis weight, or coating weight. This linearization typically uses a predetermined calibration curve. When the substrate surface has a substantially cylindrical shape (e.g., a roll machine or conveyor belt that can be seen as a flattened cylindrical shape, or a cylinder with a slightly non-circular cross-section), each location on the substrate surface may be defined by cylindrical coordinates (position along the width of the substrate surface and the rotation angle of the substrate).

[0010] The X-ray signal may be a sampled voltage or an integrated charge. The signal is typically time-averaged over a (constant) measurement period.

[0011] The specific parameters that may be used may include one or more of the following: (a) Open-circuit voltage (V 0,Sub (a) a normalization factor for the shutter open signal, (b) a spectral adjustment factor for the determined coating weight (a), and (c) a temperature compensation factor for the voltage signal (b). It should be noted that the substrate may be subject to temperature fluctuations, for example, due to heating of the substrate (e.g., in the case of a roll machine). Since these parameters are position-dependent (i.e., they differ for each position on the substrate surface), a database of parameters for a particular substrate may be provided for compensation purposes, and it may be stored in non-volatile memory.

[0012] In practice, the measured voltage may be normalized by dividing the measured voltage by a normalization factor or shutter open signal (both reduced by the saturation voltage before division). The measured voltage may be temperature-compensated by applying a temperature compensation rate (preferably together with a temperature compensation factor) to the measured voltage, preferably the measured voltage normalized by the normalization factor or shutter open signal. The spectral adjustment rate for the determined coating weight may be multiplied by the coating weight, determined from the measured voltage, preferably normalized by the normalization factor or shutter open signal, and / or compensated by the temperature compensation rate.

[0013] In one embodiment (which may be combined with any other embodiments disclosed herein), the disclosure provides a method for determining compensation parameters. This may be achieved by acquiring X-ray signals detected for each of a plurality of locations on the surface of a substrate (and generally a plurality of location-specific X-ray signals, each having different conditions for each signal). A set of compensation parameters for each location on the surface of the substrate may then be established from the respective detected X-ray signal(s).

[0014] For example, a shutter open signal for a position on the substrate may be established by measuring the position on the substrate surface when no material is placed on the substrate (e.g., no material is placed between the sensor head and the substrate). The shutter open signal for a given position may then include the detected X-ray signal obtained at that position. Effectively, in a mounting configuration using a roll machine, the bare roll machine surface is mapped. That is, each square centimeter of the roll machine surface is measured by the X-ray sensor using synchronous scanning motion across the roll machine width and the rotation angle of the roll machine.

[0015] In another embodiment, the spectral adjustment ratio may be determined by measuring the X-ray signal at each position on the surface of the substrate when a known amount of material (e.g., thickness) is placed at a predetermined position (or distance) relative to the X-ray sensor. The spectral adjustment ratio for each position may be established by comparing the amount of material determined for each position (e.g., basis weight or material weight) with the known amount of material. It is preferable that a pre-established shutter opening signal is used when determining the amount of material.

[0016] The temperature compensation ratio may be established by measuring the surface of a substrate without material on it at a different (typically higher) temperature than the measurement performed to establish the shutter open signal. The temperature compensation coefficient may be identified (usually calculated) for this temperature, and the temperature compensation ratio may be established by comparing the shutter open signal adjusted by the temperature compensation coefficient (or equivalently, another measurement performed at the first temperature with no material on the substrate) with the measured X-ray signal.

[0017] Any embodiment may be embodied as a computer program (e.g., software and / or firmware) that can be provided on a computer-readable medium. Additionally or alternatively, embodiments may be found in hardware, for example, in an X-ray analysis system. The system may include features configured to implement any of the method embodiments and / or features. These may include X-ray sensors and / or processing units (processors).

[0018] This disclosure can be implemented in many ways, and preferred embodiments may be described below, merely as examples, with reference to the accompanying drawings. [Brief explanation of the drawing]

[0019] [Figure 1] An exemplary X-ray sensor head configuration for a web measurement process is shown. [Figure 2]Depict a typical XRF calibration curve showing X-ray detector signals for different basis weights of different substrates. [Figure 3] Illustrate measurements at different positions on a cylindrical substrate. [Figure 4] Show an approach for establishing a spectral adjustment rate or slope angle rate in one embodiment. [Figure 5] Depict a flowchart of a compensation algorithm according to one embodiment. [Figure 6] Depict a flowchart of substrate mapping according to one embodiment. [Figure 7A] Depict a flowchart of an algorithm for establishing spectral adjustment parameters or slope angle parameters according to one embodiment. [Figure 7B] Depict a flowchart of an algorithm for establishing spectral adjustment parameters or slope angle parameters according to one embodiment. [Figure 8] Depict a flowchart of an algorithm resulting from establishing temperature compensation parameters according to one embodiment. [Figure 9] Depict a mapped substrate according to one embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0020] Like reference numerals indicate corresponding features. All drawings are to be understood as schematic.

[0021] In the examples considered here, XRF measurements of basis weight or coating weight on a cylindrical substrate will be described. It will be understood that different X-ray techniques and / or different material quantity measurements and / or different substrate shapes may be used as alternatives. For example, the X-ray signal may be from X-ray scattering. In such situations, it will be apparent how to modify the approaches disclosed below. Also, the measurements may in this example be made only at specific positions (referred to as "binned" values or positions) on the surface of the substrate.

[0022] The following table shows the parameters used in the specific embodiment considered at this stage.

[0023] [Table 1-1]

[0024] [Table 1-2]

[0025] Measurements of the material on the substrate (open beam measurement) are performed at specific locations identified by the cylindrical coordinates (x,φ) of the substrate, which may correlate with the binned location (X,φ). Although nominally performed at a specific time t, the measurement is actually performed over a period (T), and the voltage value is obtained from the time-averaged, integrated measurements over that period. Therefore, this measured X-ray voltage signal is identified as V(x,φ,t).

[0026] Next, referring to Figure 2, a typical XRF calibration curve is depicted showing the X-ray detector signal for different substrate basis weights. For all substrates, it can be seen that the detector signal decreases with increasing basis weight, but eventually saturates. This is the saturation voltage V s This defines the saturation voltage, which depends on the material placed on the substrate and typically does not change even if the substrate composition is adjusted.

[0027] The curve (in particular, its slope defining the mass attenuation rate and open-beam voltage of the bare substrate) varies for different substrate compositions. As can be seen from the figures shown, the correct basis weight can be identified when the correct curve is used for a particular signal (e.g., a measured voltage). Note that the curve may differ between measured locations on the substrate. The compensation techniques disclosed herein enable the identification of the correct curve for a particular substrate and a particular location on the substrate.

[0028] Compensation for substrate composition is performed using the following method (as shown algorithmically in the flowchart in Figure 5, as described below).

[0029] Firstly, open-beam measurements are compensated by normalization so that they are identical for all substrates after subtracting the saturation voltage. This is done according to equation (1) below.

[0030]

number

[0031] After substrate compensation, the measured values ​​may be temperature-compensated using the following equation (2).

[0032]

number

[0033] This is the temperature compensation coefficient (independent of location).

[0034]

number

[0035]

number

[0036] Here, the detected voltage is compensated and can be linearized using a linear calibration curve based on polynomial regression of the mass decay rate according to equation (4) below.

[0037]

number

[0038] However, the actual mass decay rate differs from that of the first-order calibration curve. Therefore, compensation for spectral changes is performed using equation (5) below.

[0039]

number

[0040] Therefore, the compensation parameter to be established is the normalized shutter opening voltage V 0,Sub These are (x,φ), temperature compensation rate b(x,φ), and spectral change rate a(x,φ). All of these are position-dependent (i.e., they may vary depending on their position on the substrate). For use during generation, they are preferably stored in a database, typically provided in non-volatile memory. A method for establishing these compensation parameters is described below.

[0041] Generally speaking, a method can be conceivable to compensate for substrate variations in measuring the amount of material of a material placed on a substrate. This method includes receiving an X-ray signal detected for measuring the material at a location on the surface of the substrate (in particular, the material is on the substrate and, optionally, in contact with the substrate), and determining the amount of material based on the received X-ray measurement signal and a predetermined set of compensation parameters for the substrate, wherein the set of compensation parameters changes according to the location on the surface of the substrate. The determination of material quality may also be based on any form of X-ray analysis, e.g., XRF analysis or X-ray scattering analysis. In some mounting configurations, the amount of material represents the material thickness, coating weight, and / or basis weight. In some mounting configurations, the material properties may also be the thickness of chemical deposition or electrodeposition, such as on a metal sheet or metal foil. The receiving and determining steps are advantageously repeated for multiple locations on the surface of the substrate.

[0042] Any of the embodiments disclosed herein may be embodied as a computer program configured to perform any of the methods disclosed herein when executed by a processing unit (or having steps corresponding to each step of the methods disclosed herein, causing the processing unit to perform such method steps). The processing unit may be coupled to an X-ray analysis system for receiving a suitable signal and / or for controlling the system in accordance with the Method.

[0043] In another embodiment, an X-ray analysis system for measuring the amount of material of a material placed on a substrate may be considered. The system may include an X-ray sensor configured to detect an X-ray signal for measuring the material at a location on the surface of the substrate, and a processing device for compensating for substrate variations in the measurement, the processing device configured to determine the amount of material based on the detected X-ray measurement signal and a predetermined set of compensation parameters for the substrate, the set of compensation parameters changing according to the location on the surface of the substrate. The system may have features according to any other embodiment disclosed herein, and / or the processing device may be configured according to any other embodiment disclosed herein.

[0044] Next, some desired and / or advantageous features in any manner will be described.

[0045] In some embodiments, the substrate surface has a cylindrical shape. Then, each position on the substrate surface may be defined by its position along the width (x) of the substrate surface and the rotation angle (φ) of the substrate.

[0046] The detected X-ray signal may include a sensor output of either a sampled voltage or an integrated charge. Typically, the X-ray signal is then time-averaged over a measurement period (e.g., a predetermined duration and / or a fixed duration).

[0047] In one embodiment, the step of determining the amount of material includes adjusting the received X-ray measurement signal according to a set of compensation parameters. The adjusted X-ray measurement signal may then be correlated with the amount of material according to a calibration relationship (between the signal and the amount of material). The calibration relationship may be represented by a curve, the parameters of which may be selected, for example, according to a standard.

[0048] In an embodiment, the set of compensation parameters includes a predetermined shutter opening signal for the substrate (or more specifically, each position on the substrate). The received X-ray measurement signal may then be adjusted by normalizing it according to the predetermined shutter opening signal (for the measured position). In an embodiment, the set of compensation parameters includes a predetermined temperature compensation rate. The received X-ray measurement signal may then be adjusted by compensating it for temperature and applying the predetermined temperature compensation rate. In an embodiment, the set of compensation parameters includes a predetermined spectral adjustment rate. The material quantity may then be determined by applying the predetermined spectral adjustment rate to the material quantity determined by correlating it according to a (standard) calibration relationship.

[0049] Further references to the general terminology used in this disclosure are provided below. First, specific details of the method for establishing the compensation parameters are described here.

[0050] An exemplary process for determining compensation parameters includes the following steps: First, perform a shutter-open voltage mapping of the substrate at room temperature. Next, perform a simulation measurement of an equivalent sample at room temperature to determine the tilt adjustment parameter or curve correction parameter. Finally, perform a simulation measurement of an equivalent sample against a roll machine at high temperature to determine the temperature compensation adjustment parameter. It is desirable that these steps be performed in this order so that the previously established parameters can be used to correctly establish the other parameters.

[0051] Referring to Figure 3, measurements at different positions on a cylindrical substrate (roll machine) are illustrated. The roll machine has a width (L) and a circumference (U). Therefore, each measurement at a specific point along the width (x) and at a specific orientation angle (φ) of the roll machine can be translated into a two-dimensional position on a plane. Measurement requires relative movement between the sensor and different positions on the cylindrical substrate. In one embodiment, the sensor is held at a specific position along the width, and the roll machine is rotated in 360-degree increments, in steps of a certain angle, so that multiple angular positions relative to its width point are measured. In another implementation, the roll machine may rotate continuously (for example, under standard operating conditions, the sensor is moved along the width and the roll machine rotation is repeated).

[0052] Shutter-open voltage mapping of the substrate is performed by measurement on a bare roll machine (i.e., a roll machine with no material on the substrate and / or no material between the substrate and the X-ray sensor).

[0053] Time-averaged and standardized substrate voltage V 0,Sub The (x,φ) (shutter-open voltage) is established for a defined time window T at a specific position on the roll machine according to the following equation (6). In other words, the shutter-open voltage is established as a voltage measurement determined when no material is placed on the substrate.

[0054]

number

[0055] As described above, the sensor remains in the same horizontal position until all data points are satisfied with respect to φ. Next, the horizontal position of the sensor is shifted with respect to φ for all data points, and this is repeated for each binned value of X.

[0056] Next, we present an approach for establishing the spectral adjustment ratio or tilt angle ratio. As mentioned above, this procedure is advantageously performed after the shutter opening voltage has been mapped to the substrate (as described above). This procedure is performed using the substrate at room temperature without placing any material on the substrate.

[0057] If desired, the first process is to verify the coating deviation. This is done by measuring the coating weight without a sample at any position on the roll machine after 2D shutter opening voltage adjustment. For all positions, the measured value is Δcw meas Ensure that the deviation does not become too large. If the coating deviation is sufficiently small, it is possible to determine the linear regression parameters for each position, and then the process can be continued.

[0058] The main process for establishing the spectral adjustment ratio or tilt angle ratio is performed on a substrate at room temperature, with no material placed on it.

[0059] Instead, a material is interposed between the substrate and the sensor, as described below. The substrate is rotated at a standard production speed.

[0060] Other substrate surfaces that exhibit periodically repeating surfaces relative to the X-ray head can also be treated similarly. For example, the surface of an elongated conveyor belt on which the object being analyzed is placed can be described by a "pseudo" angular position (φ') defined by using a cylinder with a circumference U equal to the length of the conveyor belt, essentially treating it as cylindrical. A stationary substrate (e.g., a planar substrate) can be analyzed using a Cartesian coordinate system rather than cylindrical coordinates.

[0061] Referring here to Figure 4, an approach for establishing a spectral adjustment ratio or tilt angle ratio in one embodiment is shown. This shows a sensor head 100, a sample 110 for measurement, and a substrate (roll machine) 120. For example, one or more well-known samples 110 are measured at each roll machine position due to spectral changes caused by varying compositions of the substrate 120, and therefore which may differ at different substrate positions. The number of samples 110 may depend on production and may vary significantly based on application.

[0062] It is highly desirable to have the same sample 110 at each measurement position of the roll machine. Therefore, the sample 110 is advantageously positioned at a fixed position (or distance) relative to the sensor head 100, for example, by directly attaching the sample 110 to the sensor head 100 during scanning.

[0063] Next, the sensor performs the same mapping operation as shown in Figure 3 for the bare roll machine. The following sequence is performed: The coating weight of the sample is mapped, and a linear regression a(x,φ) of the parameter set is performed at each position according to equation (7) below. Thus, the 2D array a(x,φ) defines the spectral change at each position in the measurement space and does not require any additional information regarding the chemical composition of different substrates.

[0064]

number

[0065] This process may be repeated for multiple samples 110. Several examples of the number of samples may be considered based on the characteristics of the production line under consideration. For example, if the line operates with only a single basis weight of a single coating material, it may suffice to use only this basis weight for a single sample. If the line operates with different thicknesses or different coating materials, then the samples should cover the entire measurement range to perform appropriate gain / offset adjustments. In the case of very large production ranges, it may be desirable to divide the measurement range and parameters into subsets. If the sample material 110 is brittle and cannot be directly attached to the sensor head 100 or otherwise securely positioned, it may be possible to use a similar material (with respect to XRF or Compton response) to simulate production. As a result, multiple sets of spectral adjustment ratios or tilt angle ratios may be established for different thickness ranges and / or different materials.

[0066] The set(s) resulting from the spectral adjustment coefficient or tilt angle coefficient parameter (a(x,φ)) are then usefully stored in a non-volatile memory database.

[0067] Here, we consider an approach to establish the temperature compensation ratio. Preferably, this approach is performed after both the shutter opening voltage and tilt adjustment have been successfully mapped to the substrate. Similar to the process for establishing the shutter opening voltage, the substrate is measured with no material placed on it and no material interposed between the substrate and the sensor (in other words, any sample material used for establishing the tilt adjustment is removed). The substrate (e.g., a roll machine) is heated to a temperature higher than room temperature and typically rotated at a standard production speed.

[0068] Spectral changes may result in different temperature compensation parameters for each position (x,φ). This may result in different absorptivity of the air. Since the spectrum at each position is unknown, it is measured using a heated roll machine without an external sample.

[0069] The following sequence is performed. First, the voltage is measured without a sample at each position of the roll machine after the 2D shutter opening voltage has been adapted (according to equation (6) above). Next, the temperature compensation adjustment parameter (b(x,φ)) is established for each position (x,φ) according to equation (8) below, where,

[0070]

number

[0071]

number

[0072] The resulting set of temperature compensation parameters b(x,φ) is conveniently stored in a non-volatile memory database.

[0073] Returning to the general terminology described above, further embodiments may be considered (which may be provided independently or in combination with other embodiments disclosed herein). This provides a method for determining compensation parameters for substrate variation in measuring the amount of material of a material placed on a substrate. The method includes the steps of: acquiring at least one detected X-ray signal for each of a plurality of locations on the surface of the substrate; and establishing a set of compensation parameters for each location on the surface of the substrate based on the respective at least one detected X-ray signal. In one embodiment, the acquiring step may yield one detected X-ray signal for each of a plurality of locations on the surface of the substrate (under specific different conditions). The establishing step may then yield one compensation parameter for each location on the surface of the substrate. The acquiring and establishing steps may then be repeated for different types of compensation parameters. As can be understood in alternative terms, the acquiring step may yield multiple detected X-ray signals for each of a plurality of locations on the surface of the substrate (generally acquired at different times and under different conditions). The establishing step may then yield multiple compensation parameters for each location on the surface of the substrate.

[0074] All of the details described above (referencing, for example, the general terms of this disclosure) may apply to the present embodiments. For example, the acquired detected X-ray signal may include a sensor output of either a sampled voltage or an integrated charge. Typically, the X-ray signal is then time-averaged over the measurement period. Possible compensation parameters are then described.

[0075] For example, the set of compensation parameters may include a shutter open signal for the substrate. Next, at least one detected X-ray signal may include an X-ray signal obtained for each position on the surface of the substrate when no material is placed on the substrate (at a first temperature, e.g., room temperature). Next, establishing the set of compensation parameters may include defining a shutter open signal for each position on the surface of the substrate by each acquired detected X-ray signal (which may include a sensor output that is either a sampled voltage or an integrated charge, and typically the X-ray signal is then time-averaged over the measurement period as described above).

[0076] In another embodiment, the set of compensation parameters includes a spectral adjustment ratio for the substrate. Next, at least one detected X-ray signal may include an X-ray signal obtained for each position on the surface of the substrate when a known amount of material is placed at a predetermined position (or distance) relative to the X-ray sensor. For example, the known amount of material may be attached to the X-ray sensor. Next, establishing the set of compensation parameters may include identifying the amount of material for each position by correlating the X-ray measurement signal derived from the X-ray measurement signal acquired for each position with the amount of material, according to the calibration relationship, and establishing a spectral adjustment ratio for each position on the surface of the substrate by comparing the identified amount of material with the known amount of material. Advantageously, the X-ray measurement signal derived from the acquired X-ray measurement signal includes the acquired X-ray measurement signal for each position, with respect to the shutter opening signal for each position.

[0077] In a further embodiment, the set of compensation parameters includes a temperature compensation rate of the substrate. Next, at least one detected X-ray signal may include the X-ray signal acquired for each position on the surface of the substrate when no material is disposed on the substrate at a second different temperature (typically higher than the first temperature). Next, establishing the set of compensation parameters may include calculating a temperature compensation coefficient for the second temperature and comparing the X-ray signal acquired for each position at the first temperature adjusted by the temperature compensation coefficient with the acquired X-ray signal acquired for each position at the second temperature to establish a temperature compensation rate for each position on the surface of the substrate.

[0078] Next, referring to FIG. 5, a flowchart of the compensation algorithm is depicted. It can be seen that this follows the above discussion regarding the method of compensating voltage measurements. This includes the steps of measuring the voltage while the system is in an online measurement state, determining the measured sensor head position (x, φ), compensating the voltage for substrate measurement using the open shutter voltage for that position (V 0,sub (x, φ)), performing temperature compensation using the temperature compensation rate (calibration parameter), b(x, φ), linearizing the measurement using a standard calibration curve, performing spectral adjustment of the measurement using the spectral adjustment rate, a(x, φ), and performing data post-processing (profile, interface update, etc.). Next, the system stops the online measurement and proceeds to a standby position. Although voltage measurement is shown in this regard, the same technique can be equally applied to charge measurement.

[0079] FIG. 6 depicts a flowchart of substrate mapping according to the above procedure. First, the system determines that a new substrate map is being generated and that the roll machine scan is at the operating speed. The first loop is in the step of size X step where X = X min from X maxHorizontal scanning is performed until the first loop. Within the first loop, the second loop performs angular scanning, but the number of iterations (i(φ)) is smaller than the integration time divided by the sampling rate. For each execution of the second loop, the following steps are performed: voltage measurement V raw The following steps are performed: the angle roll machine position (φ) is determined, the number of iterations (i(φ)) is incremented, and the voltage measurement value changes from V0 to V norm Normalized by V(x,φ), V norm It is incremented by . Within the first loop, after the second loop is completed, the following steps are performed: V(x,φ) is defined as V(x,φ) / i(φ), and V(x,φ) is then stored in the database.

[0080] Figures 7A and 7B illustrate flowcharts of the algorithm for establishing spectral adjustment parameters or tilt angle parameters. This follows the procedure described above. The first loop performs surface mapping in the measurement space without additional samples. For each position, a voltage is measured, but the measured voltage is compensated using the open shutter voltage for that position. The compensated voltage is the measured basic width cw meas To find the basic width |cw, the basic width is linearized according to the basic calibration and measured. meas |However, the maximum permissible measured coating weight difference Δcw before compensation is made. meas If the above conditions are met, the process is stopped (and restarted). Otherwise, the process continues with the procedure for each sample, starting with the sample being placed in front of the sensor holder (as shown in Figure 4). The second loop performs surface mapping in the measurement space with the placed sample, using the following steps for each position: a voltage is measured; the measured voltage is compensated using the open shutter voltage for that position; the compensated voltage is linearized according to the base calibration; and the measurement mapping is performed in CW i This is performed to satisfy (x,φ). Once the second loop is complete for all samples, coating weight regression is performed to determine a(x,φ), and the determined parameters are stored in the database.

[0081] Figure 8 illustrates a flowchart of the algorithm for establishing temperature compensation parameters according to one embodiment. This also follows the procedure described above. Surface mapping is performed for each position in a measurement space where no sample is placed, using the following steps: a voltage is measured, the measured voltage is compensated using the open shutter voltage for that position, and a temperature compensation adjustment parameter (b(x,φ)) is established for the position according to equation (8) above. Once the loop is complete, the determined parameters are stored in the database.

[0082] The time required for calibration (determination of compensation parameters) can be estimated as follows. The first step (for example, bare roll machine mapping using the flowchart in Figure 6) may have a duration given by the following formula.

[0083]

number

[0084] This could actually take about 3 hours.

[0085] The second step (for example, spectral adjustment according to the flowcharts in Figures 7A and 7B) may have durations for each sample as given by the following formula.

[0086]

number

[0087] This could actually take about 3 hours.

[0088] The third step (for example, temperature compensation adjustment according to the flowchart in Figure 8) may have durations for each sample as given by the following formula.

[0089]

number

[0090] This could actually take about 3 hours.

[0091] Therefore, in practice, the estimated total time for N samples is 3h + N * This may be given by 3 hours plus additional warm-up time for the board as needed.

[0092] Figure 9 illustrates a 2D array of spectral adjustment parameters (a(x,φ)) and temperature adjustment parameters (b(x,φ)) stored in a database according to one embodiment. The figure is for a roll machine with a width of 100 length units (e.g., mm, cm, m). For measurement, the width is subdivided into 10 equal parts between 5 and 95, and the circumference is subdivided into 10 equal angular parts between 18 and 342. The first two columns corresponding to x=5 and x=15 are filled for the orientation angles φ=18° to 342° of the roll machine. It is understood that when the mapping is complete, all cells will be filled with specific values ​​of a(x,φ) and b(x,φ).

[0093] Where used herein, including in the claims, singular terms are interpreted as including plural forms unless otherwise specified in context. For example, unless otherwise specified in context, singular references in the claims, such as "a" or "an" (e.g., analog-to-digital converter), mean "one or more" (e.g., one or more analog-to-digital converters). Throughout the specification and claims of this disclosure, words such as "comprise," "including," "having," and "contain," as well as variations of these words, such as "comprising" and "comprises" or similar, mean "including but not limited to" and are not intended to exclude other components.

[0094] The following numbered paragraphs 1 to 24 provide various examples of the embodiments disclosed herein. Paragraph 1. A method for compensating for substrate variation in measuring the amount of material of a material placed on a substrate, the method comprising: receiving a detected X-ray signal for measuring the material at a location on the surface of the substrate; and determining the amount of material based on the received X-ray measurement signal and a predetermined set of compensation parameters for the substrate, wherein the set of compensation parameters changes according to the location on the surface of the substrate. Paragraph 2. The method according to Paragraph 1, wherein the substrate surface has a substantially cylindrical shape, and each position on the substrate surface is defined by a position along the width of the substrate surface and the rotation angle of the substrate. Paragraph 3. The method according to Paragraph 1 or Paragraph 2, wherein the amount of material indicates the material weight and / or the material basis weight. Paragraph 4. The method according to any one of paragraphs 1 to 3, wherein the amount of material indicates the weight, basis weight, or thickness of the deposit or coating. Paragraph 5. The method according to any one of paragraphs 1 to 4, wherein the detected X-ray signal is a sensor output comprising either a sampled voltage or an integrated charge, and a time-averaged sensor output over a measurement period. Paragraph 6. The method according to any one of paragraphs 1 to 5, wherein the receiving step and the determining step are repeated for a plurality of locations on the surface of the substrate. Paragraph 7. The method according to any one of paragraphs 1 to 6, wherein the step of determining the amount of material includes adjusting the received X-ray measurement signal according to a set of compensation parameters and correlating the adjusted X-ray measurement signal with the amount of material according to a calibration relationship. Paragraph 8. The method according to any one of paragraphs 1 to 7, wherein the set of compensation parameters includes a predetermined shutter opening signal for the substrate, and adjusting the received X-ray measurement signal includes normalizing the received X-ray measurement signal according to the predetermined shutter opening signal. Paragraph 9. The method according to any one of paragraphs 1 to 8, wherein the set of compensation parameters includes a predetermined temperature compensation rate, and adjusting the received X-ray measurement signal includes compensating the received X-ray measurement signal for temperature and applying the predetermined temperature compensation rate. Paragraph 10. The method according to any one of paragraphs 1 to 9, wherein the set of compensation parameters includes a predetermined spectral adjustment rate, and determining the amount of material includes applying the predetermined spectral adjustment rate to the amount of material determined by correlating according to the calibration relationship. Paragraph 11. A method for determining compensation parameters for substrate variation in the measurement of the amount of material of a material placed on a substrate, the method comprising: acquiring at least one detected X-ray signal for each of a plurality of locations on the surface of the substrate; and establishing a set of compensation parameters for each of the locations on the surface of the substrate based on the respective at least one detected X-ray signal. Paragraph 12. The method according to Paragraph 11, wherein the set of compensation parameters includes a shutter open signal for the substrate, and the at least one detected X-ray signal includes an X-ray signal acquired for each position on the surface of the substrate when no material is placed on the substrate at a first temperature, and establishing the set of compensation parameters includes defining the shutter open signal for each position on the surface of the substrate by the respective acquired detected X-ray signals. Paragraph 13. The method according to Paragraph 11 or 12, wherein the set of compensation parameters includes a spectral adjustment rate for the substrate, and the at least one detected X-ray signal includes an X-ray signal obtained for each position on the surface of the substrate when a known amount of material is placed at a predetermined position relative to an X-ray sensor, and establishing the set of compensation parameters includes identifying the amount of material for each position by correlating the X-ray measurement signal derived from the obtained X-ray measurement signal for each position with the amount of material according to a calibration relationship, and establishing the spectral adjustment rate for each position on the surface of the substrate by comparing the identified amount of material with the known amount of material. Paragraph 14. The method according to any one of paragraphs 11 to 13, wherein the X-ray measurement signal derived from the acquired X-ray measurement signal includes the acquired X-ray measurement signal for each of the respective positions due to the shutter opening signal for each of those positions. Paragraph 15. The method according to any one of paragraphs 11 to 14, wherein the set of compensation parameters includes a temperature compensation factor for the substrate, and the at least one detected X-ray signal includes an X-ray signal obtained for each position on the surface of the substrate when no material is placed on the substrate at a second different temperature, and establishing the set of compensation parameters includes calculating a temperature compensation factor for the second temperature, and establishing the temperature compensation factor for each position on the surface of the substrate by comparing the X-ray signal obtained for each position at the first temperature adjusted by the temperature compensation factor with the X-ray signal obtained for each position at the second temperature. Paragraph 16. A method of any of paragraphs 1 to 10, further comprising a method of any of paragraphs 11 to 15. Paragraph 17. A computer-readable medium containing a computer program, wherein the computer program is configured to perform the method described in any one of paragraphs 1 to 10 when executed by a processing unit. Paragraph 18. An X-ray analysis system for measuring the amount of material of a material placed on a substrate, comprising: an X-ray sensor configured to detect an X-ray signal for measuring the material at a location on the surface of the substrate; and a processing device for compensating for substrate variations in the measurement, the processing device configured to determine the amount of material based on the detected X-ray measurement signal and a predetermined set of compensation parameters for the substrate, wherein the set of compensation parameters changes depending on the location on the surface of the substrate.

[0095] The embodiments described herein are described with reference to a particular type of apparatus and application (in particular, XRF analysis of roll machine-based industrial processes), and while the embodiments have particular advantages in such cases as discussed herein, the approaches described herein may also be applicable to other types of apparatus and / or applications. Specific structural details of the X-ray system may be substantially modified to arrive at a device having similar or identical operation, although this may be potentially advantageous (in particular, considering the limitations and capabilities of known X-ray systems). Each feature disclosed herein may be replaced by alternative features serving the same, equivalent, or similar purpose unless otherwise specified. Thus, unless otherwise specified, each feature disclosed is merely an example of a general set of equivalent or similar features.

[0096] Any and all examples or illustrative language provided herein (such as "for instance," "such as," "for example," etc.) are used solely to better illustrate the invention and not to limit its scope, and unless otherwise claimed, they are within the scope of the invention. No language herein should be construed as indicating an element not claimed to be essential to the practice of the invention.

[0097] Any of the steps described herein may be performed in any order or concurrently, unless otherwise stated or the context requires otherwise.

[0098] All embodiments and / or features disclosed herein can be combined in any combination, except for any combination in which at least some of such features and / or processes are mutually exclusive. There may be specific combinations of embodiments that yield further benefits, such as embodiments for determining a set of compensation parameters and applying the set of compensation parameters to measurements, as described herein. In particular, preferred features of the present invention are applicable to all embodiments of the present invention and can be used in any combination. Similarly, features described in non-essential combinations can be used separately (rather than in combination).

Claims

1. A method for compensating for substrate fluctuations in the measurement of a material placed on a substrate, wherein the method is The process involves receiving the detected X-ray measurement signal of the material at a location on the surface of the substrate, Determining the amount of material based on the received X-ray measurement signal and a predetermined set of compensation parameters for the substrate, wherein the set of compensation parameters varies according to the position on the surface of the substrate, A method wherein the surface of the substrate has a substantially cylindrical shape, and each position on the surface of the substrate is defined by a position along the width of the surface of the substrate and the rotation angle of the substrate.

2. The method according to claim 1, wherein the amount of material refers to the material weight and / or the material basis weight.

3. The method according to claim 1, wherein the amount of material indicates the weight, basis weight, or thickness of the deposit or coating.

4. The method according to claim 1, wherein the detected X-ray measurement signal is a sensor output comprising either a sampled voltage or an integrated charge, and a time-averaged sensor output over a measurement period.

5. The method according to claim 1, wherein the receiving and determining are repeated for a plurality of positions on the surface of the substrate.

6. The method according to claim 1, wherein determining the amount of material includes adjusting the received X-ray measurement signal according to the set of compensation parameters and correlating the adjusted X-ray measurement signal with the amount of material according to the calibration relationship.

7. The method according to claim 6, wherein the set of compensation parameters includes a predetermined shutter opening signal for the substrate, and adjusting the received X-ray measurement signal includes normalizing the received X-ray measurement signal according to the predetermined shutter opening signal.

8. The method according to claim 6, wherein the set of compensation parameters includes a predetermined temperature compensation rate, and adjusting the received X-ray measurement signal includes compensating the received X-ray measurement signal for temperature and applying the predetermined temperature compensation rate.

9. The method according to claim 1, wherein the set of compensation parameters includes a predetermined spectral adjustment rate, and determining the amount of material includes applying the predetermined spectral adjustment rate to the amount of material determined by correlation according to a calibration relationship.

10. A method for determining compensation parameters for substrate variation in measuring the amount of material of a material placed on a substrate, wherein the method is To acquire at least one detected X-ray signal for each of the multiple locations on the surface of the substrate, This includes establishing a set of compensation parameters for each position on the surface of the substrate based on each of the at least one detected X-ray signals, A method for determining compensation parameters for substrate variation in measuring the amount of material of a material placed on a substrate, wherein the surface of the substrate has a substantially cylindrical shape, and each position on the surface of the substrate is defined by a position along the width of the surface of the substrate and the rotation angle of the substrate.

11. The method according to claim 10, wherein the set of compensation parameters includes a shutter open signal for the substrate, and the at least one detected X-ray signal includes an X-ray signal acquired for each position on the surface of the substrate when no material is placed on the substrate at a first temperature, and establishing the set of compensation parameters includes defining the shutter open signal for each position on the surface of the substrate by each of the acquired at least one detected X-ray signals.

12. The method according to claim 10, wherein the set of compensation parameters includes a spectral adjustment rate for the substrate, the at least one detected X-ray signal includes an X-ray signal obtained for each position on the surface of the substrate when a known amount of material is placed at a predetermined position relative to an X-ray sensor, and establishing the set of compensation parameters includes identifying the amount of material for each of the positions by correlating the X-ray signal derived from the at least one detected X-ray signal obtained for each of the positions with the amount of material according to a calibration relationship, and establishing the spectral adjustment rate for each position on the surface of the substrate by comparing the identified amount of material with the known amount of material.

13. The method according to claim 11, wherein the X-ray signal obtained for each position, derived from the acquired at least one detected X-ray signal, includes the shutter open signal for each of the positions, and the X-ray signal obtained for each of the positions.

14. The method according to claim 10, wherein the set of compensation parameters includes a temperature compensation rate for the substrate at a first temperature, and the at least one detected X-ray signal includes an X-ray signal obtained for each position on the surface of the substrate when no material is placed on the substrate at a second temperature, and establishing the set of compensation parameters includes calculating a temperature compensation coefficient for the substrate at a second temperature, and establishing the temperature compensation rate for each position on the surface of the substrate by comparing the X-ray signal obtained for each of the positions at the first temperature, adjusted by the temperature compensation coefficient, with the X-ray signal obtained for each of the positions at the second temperature.

15. A method for compensating for substrate fluctuations in the measurement of a material placed on a substrate, wherein the method is To acquire at least one detected X-ray signal for each of the multiple locations on the surface of the substrate, Based on each of the at least one detected X-ray signals, a set of compensation parameters is established for each position on the surface of the substrate. The process involves receiving the detected X-ray measurement signal of the material at a location on the surface of the substrate, Determining the amount of material based on the received X-ray measurement signal and a predetermined set of compensation parameters for the substrate, wherein the set of compensation parameters varies according to the position on the surface of the substrate, A method wherein the surface of the substrate has a substantially cylindrical shape, and each position on the surface of the substrate is defined by a position along the width of the surface of the substrate and the rotation angle of the substrate.

16. A computer-readable medium containing a computer program, wherein the computer program is configured to perform the method described in claim 1 when executed by a processing unit.

17. An X-ray analysis system for measuring the amount of material of a material placed on a substrate, wherein the system An X-ray sensor configured to detect the X-ray measurement signal of the material at a position on the surface of the substrate, A processing apparatus for compensating for substrate fluctuations in the measurement, comprising: a processing apparatus configured to determine the amount of material based on a detected X-ray measurement signal and a predetermined set of compensation parameters for the substrate, wherein the set of compensation parameters changes according to the position on the surface of the substrate; An X-ray analysis system for measuring the amount of material of a material placed on a substrate, wherein the surface of the substrate has a substantially cylindrical shape, and each position on the surface of the substrate is defined by a position along the width of the surface of the substrate and the rotation angle of the substrate.

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