Calibration measurement method and module of capacitance level meter and storage medium
The capacitor level meter is calibrated through segmented interpolation algorithm and low-pass filtering technology, which solves the problems of low measurement accuracy and electromagnetic interference in low dielectric constant media, realizes high-precision liquid level control, and improves the production efficiency and measurement stability of semiconductor factories.
Patent Information
- Application Number
- CN202510834348.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-20
- Publication Date
- 2025-09-02
AI Technical Summary
Existing capacitance level meters have low measurement accuracy in low dielectric constant media and are susceptible to electromagnetic interference, which cannot meet the liquid level control needs of ultra-pure water production in semiconductor factories.
The capacitor level meter is calibrated and measured by segmented interpolation algorithm, and linear interpolation calculation is performed in each interval by aliquoting the capacitance interval and performing linear interpolation calculation, combining low-pass filtering technology to suppress electromagnetic interference and improve measurement accuracy.
In low dielectric constant medium, the measurement accuracy is improved to ±0.25%, and the stability is improved by 5.3%, solving nonlinear errors and disturbance problems, ensuring the accuracy and production efficiency of liquid level control.
Smart Images
Figure CN120576845A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of intelligent sensing, and in particular relates to a calibration measurement method, a module and a storage medium of a capacitance level meter. Background Art
[0002] A capacitance level meter uses the principle of capacitance measurement to measure the level of liquid or solid materials. Its operating principle is to place the sensor in contact with the medium within a container, forming a capacitor between the sensor's electrodes and the container wall. Changes in material position cause a change in capacitance. This capacitance change is then captured and converted by a circuit to generate a corresponding output signal for the material level.
[0003] Capacitance level meters are widely used. For example, in semiconductor manufacturing, ultrapure water is required for wet cleaning before and after various processes, such as wafer cleaning, etching, and polishing. Ultrapure water wet cleaning removes contaminants such as metal ions, organic matter, bacteria, microorganisms, particulate matter, silicon, and dissolved gases to ensure product yield. The cleaning process requires real-time control of the ultrapure water feed and discharge levels for precise level control. Capacitance level meters, due to their unique measurement principles and methods, can provide accurate level measurement during the ultrapure water production and manufacturing process in semiconductor factories.
[0004] In actual use, due to the particularity of on-site working conditions, the electromagnetic interference of electronic components in on-site high-power equipment and on-site production processes will cause the actual test accuracy of existing capacitance level meters to decrease when interfered with. Especially under working conditions where the dielectric constant of the medium is low and the dielectric constant of the medium varies greatly with the environment and temperature, the measurement accuracy of conventional capacitance level meters cannot be guaranteed.
[0005] Therefore, conventional measurement methods and calculation conversion methods cannot maintain liquid level measurement in areas with large ranges, low dielectric constants, and complex working conditions.
[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention
[0007] The object of the present invention is to provide a calibration measurement method, module and storage medium for a capacitance level meter, which can solve the problems of low measurement accuracy and unsuitability for low dielectric constant media in existing capacitance level meters.
[0008] In order to achieve the above object, a specific embodiment of the present invention provides the following technical solutions:
[0009] A calibration and measurement method for a capacitance level meter comprises: performing calibration measurement on the level in a container using the capacitance level meter to obtain a set of reference capacitance values and reference level values corresponding to the reference capacitance values; dividing the set of reference capacitance values into equal parts to form a plurality of capacitance intervals; and determining, within each of the capacitance intervals, a correspondence between capacitance values and level values using an interpolation algorithm based on the reference capacitance values and the reference level values.
[0010] In one or more embodiments of the present invention, the interpolation algorithm includes linear interpolation.
[0011] In one or more embodiments of the present invention, the interpolation function of the linear interpolation method is:
[0012]
[0013] Where, kz=An[C i+1 ]-An[C i ];
[0014] Where H x is the actual material level value, ad.x is the actual capacity value, (float)(AD[C i ]) is the minimum reference capacitance value of the capacitance range of the actual capacitance value currently measured, D is the equal division value, An[C i ] is the reference level value corresponding to the current actual measurement, An[C i+1 ] is the reference level value corresponding to the next actual measurement.
[0015] In one or more embodiments of the present invention, the measurement method further includes: obtaining the actual capacitance value of the capacitance level meter when actually measuring the level value; determining the capacitance value interval in which the actual capacitance value is located, and outputting the actual level value based on the correspondence between the capacitance value and the level value within the capacitance value interval.
[0016] In one or more embodiments of the present invention, the measurement method further includes: determining whether the actual capacitance value is within a measuring range; if not, correcting or reporting an error for the actual capacitance value.
[0017] In one or more embodiments of the present invention, the measurement method further includes determining the measurement range based on a range of the reference capacitance value.
[0018] In one or more embodiments of the present invention, the measurement method further includes: when obtaining the actual capacitance, performing low-pass filtering on the capacitance sampling signal generated by the capacitance level meter.
[0019] In one or more embodiments of the present invention, the lengths of the tolerance intervals are equal.
[0020] A specific embodiment of the present invention further provides a measurement module for a capacitance level meter, comprising: at least one processor; and a memory, wherein the memory stores instructions, and when the instructions are executed by the at least one processor, the at least one processor executes the above-mentioned calibration measurement method for the capacitance level meter.
[0021] A specific embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores executable instructions, and when the instructions are executed, the computer executes the above-mentioned calibration measurement method for the capacitance level meter.
[0022] Compared with the prior art, the calibration measurement method, module and storage medium of the capacitance level meter of the present invention improve the local fitting accuracy through a segmented interpolation algorithm, and solve the problems of nonlinear error, precision error and disturbance when using a capacitance level meter to measure the level range in a low dielectric constant medium. It can support the influence of the dielectric constant change caused by the dielectric constant changing with temperature / pressure / medium type itself. Without changing the original measurement principle and the structure of the capacitance level meter, the measurement accuracy can be improved by the interpolation calibration method. The actual control accuracy is higher, the production efficiency at the use site is improved, and unnecessary waste is avoided. Compared with other types of similar products, this interpolation method is more cost-effective and highly reproducible. Through algorithm program control, the consistency of the capacitance level meter can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0024] Figure 1 The figure is a flow chart of a calibration measurement method of a capacitance level meter according to an embodiment of the present invention.
[0025] Figure 2 Schematic diagram of measurement of a capacitance level meter in one embodiment of the present invention.
[0026] Figure 3 This is a partial flow chart of a measurement method in one embodiment of the present invention.
[0027] Figure 4 1 is a level value-capacity value curve obtained based on the measurement method in one embodiment of the present invention.
[0028] Figure 5 FIG. 4 is a schematic structural diagram of a measurement module in an embodiment of the present invention. DETAILED DESCRIPTION
[0029] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.
[0030] The terms "coupled," "connected," or "connected" as used in this specification encompass both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrically conductive medium, which may have parasitic inductance or capacitance. An indirect connection may also include a connection through other active or passive devices, such as switches, follower circuits, or other circuits or components, to achieve the same or similar functional objectives. Furthermore, in the invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another and do not necessarily require or imply a specific relationship, quantity, or order between these technical features.
[0031] In the detailed description of the specification, reference is made to the accompanying drawings forming a part hereof, wherein like reference numerals designate like parts throughout, and wherein exemplary embodiments that may be implemented are shown by way of example. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present application. Therefore, the following detailed description should not be construed in a limiting sense.
[0032] The various operations in the specification may be described as multiple discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be interpreted as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in an order different from the described embodiments. Various additional operations may be performed and / or the described operations may be omitted in additional embodiments.
[0033] For the purposes of this application, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of this application, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).
[0034] Various components and devices may be referred to or shown herein in the singular, but this is merely for ease of discussion, and any element referred to in the singular may include a plurality of such elements in accordance with the teachings herein.
[0035] The description uses the phrases "in one embodiment" or "in other embodiments" or "in some embodiments", which can each refer to one or more of the same or different embodiments. In addition, the terms "including", "comprising", "having", etc. used in relation to the embodiments of this application are synonymous.
[0036] Existing capacitance level meters typically consist of two insulated, coaxial cylindrical plates forming the inner and outer electrodes. When a dielectric with a specific dielectric constant is placed between the plates, the capacitance between them can be calculated using the formula x = 2πεL / ln(Dt / d), where L is the length of the overlapping portion of the plates, Dt is the diameter of the outer electrode, d is the diameter of the inner electrode, and ε is the dielectric constant of the dielectric medium.
[0037] When the dielectric constant of the medium is low, the capacitance change caused by the actual increase / decrease of the liquid level is also small. At the same time, the nonlinear change in the length of the overlapping part of the two plates will also cause large fluctuations in the capacitance.
[0038] Current capacitance level meter calibration methods often use a simple linear fitting method: Y = Kx + b, where the liquid level Y is proportional to the capacitance value x. A small change in capacitance results in a small change in liquid level, which in turn leads to large errors in the actual measured liquid level and is unable to meet the actual level control requirements for ultrapure water.
[0039] Furthermore, under normal circumstances, due to the inherent influence of the field equipment system, the actual measurement of a capacitive level meter will change with changes in the interface. In other words, the actual measurement is continuous, not a single point measurement. With continuous measurement, changes in the actual capacitance value will affect the measurement result of the level meter, resulting in a large error between the measurement result and the actual liquid level.
[0040] In order to solve the above problems, the present invention provides a calibration measurement method for a capacitance level meter.
[0041] like Figure 1 As shown, a calibration measurement method for a capacitance level meter in one embodiment of the present invention includes:
[0042] The capacitance level meter is used to calibrate and measure the material level in the container to obtain a set of reference capacitance values and reference level values corresponding to the reference capacitance values.
[0043] Combine Figure 2As shown, in one embodiment, the medium level in the container can be changed first, and the level can be measured by a capacitance level meter to generate a capacitance sampling signal, while the level value in the container is recorded. Then, the capacitance sampling signal is converted to digital and amplified to obtain a series of discrete capacitance sampling data X1, X2, X3, ..., Xn. These capacitance sampling data can be directly used as reference capacitance for subsequent calculations, or they can be converted into real capacitance data based on the correspondence between the sampling value and the actual capacitance value and then used as the reference capacitance for subsequent calculations. Finally, the reference capacitance values X1, X2, X3, ..., Xn and the level values Y1, Y2, Y3, ..., Yn form a set of discrete data with one-to-one correspondence.
[0044] Preferably, when the medium level in the container changes, the minimum level and the maximum level are passed, and the reference capacitance value and the reference level value corresponding to the minimum level, as well as the reference capacitance value and the reference level value corresponding to the maximum level are recorded at the same time to obtain the full range of the capacitance level meter.
[0045] Next, the set of reference capacitance values is divided equally into a plurality of capacitance intervals.
[0046] In one embodiment, the lengths of the capacitance intervals are equal. For example, the maximum value Xmax and minimum value Xmin of the reference capacitance can be determined first, and the capacitance range Xmax-Xmin can be calculated based on the difference between the two values. Then, the capacitance range can be divided into multiple capacitance intervals using a dividing value D. The dividing value D can be adjusted based on the range and actual needs.
[0047] Due to the different measured media, the capacitance range will vary greatly. By first determining the range and then dividing the capacitance range according to the range, it is helpful to avoid inaccurate calibration when measuring different media (especially those with low dielectric constants) and large accuracy output errors.
[0048] In other embodiments, the lengths of the various tolerance intervals may also be different, and the various tolerance intervals may be divided according to actual needs.
[0049] Then, within each capacity value interval, the corresponding relationship between the capacity value and the level value is determined by an interpolation algorithm based on the reference capacity value and the reference level value.
[0050] The interpolation algorithm may be a linear interpolation method, wherein the interpolation function of the linear interpolation method is expressed as a straight line passing through the two reference level values within the capacitance range.
[0051] In one embodiment, the interpolation function of the linear interpolation method is:
[0052]
[0053] Where, kz=An[C i+1]-An[C i ];
[0054] Where H x is the actual material level value, ad.x is the actual capacity value, (float)(AD[C i ]) is the minimum reference capacitance value of the capacitance range of the actual capacitance value currently measured, D is the equal division value, An[C i ] is the reference level value corresponding to the current actual measurement, An[C i+1 ] is the reference level value corresponding to the next actual measurement.
[0055] It can be seen that by establishing the interpolation function, the capacitance value and the level value are unique within each capacitance value range, ensuring that one capacitance value corresponds to only one level value, thereby realizing the calibration of the level value and the capacitance value, which is beneficial to improving the measurement accuracy.
[0056] like Figure 3 As shown, the measurement method may further include: obtaining an actual capacitance value when the capacitance level meter actually measures the level value.
[0057] In one embodiment, when actually measuring the level value, the capacitance sampling signal generated by the capacitance level meter can be collected in real time. Then, the capacitance sampling signal is amplified and analog-to-digital converted to obtain a digital capacitance sampling signal, which is used as the actual capacitance value.
[0058] Preferably, when obtaining the actual capacitance value, the capacitance sampling signal generated by the capacitance level meter may be low-pass filtered.
[0059] For example, the digital capacitance sampling signal can be low-pass filtered. This filtering effectively suppresses the impact of external electromagnetic interference on real-time capacitance acquisition, stabilizing the capacitance level meter's measurement accuracy to ±0.5% in an electromagnetic interference environment, improving stability by over 5.3%.
[0060] Next, determine whether the actual capacitance value is within the range. If not, correct the actual capacitance value. If it is within the range, proceed to the next step.
[0061] The measuring range is determined by the range of the reference capacitance.
[0062] For example, if the actual capacitance value is less than the minimum value of the measuring range, the actual capacitance value is corrected to the minimum value of the measuring range. If the actual capacitance value is greater than the maximum value of the measuring range, the actual capacitance value is corrected to the maximum value of the measuring range.
[0063] In other embodiments, if the actual capacitance value is not within the measuring range, an error may be directly reported. Alternatively, it is not necessary to determine whether the actual capacitance value is within the measuring range.
[0064] Next, the capacity interval in which the actual capacity value is located is determined, and the actual level value is output based on the corresponding relationship between the capacity value and the level value within the capacity interval.
[0065] In one embodiment, the capacitance range in which the actual capacitance lies can be determined using the following formula:
[0066]
[0067] Among them, C i The integer part of is the serial number of the capacitance interval where the actual capacitance value is located, X min This is the minimum value of the reference capacitance.
[0068] Finally, the actual capacitance value is substituted into the interpolation function corresponding to the capacitance interval in which it is located to obtain the actual level value.
[0069] In this solution, by dividing the capacitance range into multiple intervals and performing independent interpolation calculations in each interval, the local fitting accuracy is improved, and the problem of insufficient measurement accuracy caused by the nonlinear correspondence between the medium level value and the capacitance value in actual work is solved.
[0070] Figure 4 The dotted line in the middle shows the relationship curve between the level value and the capacitance value obtained by the traditional interpolation algorithm, and the solid line shows the relationship curve between the level value and the capacitance value obtained based on this solution. It can be seen that in the traditional linear interpolation algorithm, since data segmentation is not performed, when the level value and the capacitance value have a nonlinear correspondence, the error of the intermediate data will increase sharply. However, the independent interpolation between the intervals in this solution better matches the nonlinear segments, which is especially suitable for media with low dielectric constants (ε<2.8). It can reduce the measurement accuracy error from ±1% to ±0.25%, breaking through the problems of low accuracy, poor repeatability, poor long-term stability, and output signal drift of capacitance level meters when measuring the level height of media with low dielectric constants.
[0071] Compared to traditional cubic spline interpolation, this approach offers the following advantages: fewer sampling points, simplicity, and ease of implementation. For a given set of distinct reference capacitance and reference level values, the interpolation polynomial is unique, and the corresponding output level measurement value is more accurate. This approach is particularly suitable for situations with fewer data points.
[0072] In summary, this solution achieves high-precision, highly interference-resistant level measurement for capacitance level meters. Simply by configuring the software algorithm within the slave computer program and approximating the capacitance value collected by the capacitance level meter with the actual level through interpolation, the actual level value corresponding to different capacitance values can be obtained. Without changing the original measurement principle or the structure of the capacitance level meter, this interpolation calibration method can improve measurement accuracy and actual control accuracy, increase production efficiency at the site of use, and avoid unnecessary waste. Compared with other similar products of the same type, this interpolation method is more cost-effective and highly reproducible. Through algorithmic program control, consistency of capacitance level meters can be achieved.
[0073] like Figure 5 As shown, this embodiment also provides a measurement module for a capacitance level meter, wherein the measurement module 10 includes at least one processor 11, a memory 12 (e.g., a non-volatile memory), an internal memory 13, and a communication interface 14, and the at least one processor 11, the memory 12, the internal memory 13, and the communication interface 14 are connected together via a bus 15. The at least one processor 11 executes at least one computer-readable instruction stored or encoded in the memory 12. It can be understood that when the computer-executable instructions stored in the memory 12 are executed, the at least one processor 11 performs the above-mentioned calibration measurement method for the capacitance level meter.
[0074] This embodiment further provides a computer-readable storage medium, which stores executable instructions. When the instructions are executed, the computer executes the calibration measurement method for the capacitance level meter.
[0075] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0076] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0077] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.
[0078] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.
[0079] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.
[0080] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.
Claims
1. A calibration measurement method for a capacitance level meter, characterized in that: include: Calibrate and measure the level in the container using the capacitance level meter to obtain a set of reference capacitance values and reference level values corresponding to the reference capacitance values; Dividing the reference capacitance values of the group into equal parts to form a plurality of capacitance intervals; In each of the capacity value intervals, a corresponding relationship between the capacity value and the level value is determined by an interpolation algorithm based on the reference capacity value and the reference level value.
2. The calibration measurement method for a capacitance level meter according to claim 1, characterized in that: The interpolation algorithm includes a linear interpolation method.
3. The calibration measurement method for a capacitance level meter according to claim 2, characterized in that: The interpolation function of the linear interpolation method is: Where, kz=An[C i+1 ]-An[C i ]; Where H x is the actual material level value, ad.x is the actual capacity value, (float)(AD[C i ]) is the minimum reference capacitance value of the capacitance range of the actual capacitance value currently measured, D is the equal division value, An[C i ] is the reference level value corresponding to the current actual measurement, An[C i+1 ] is the reference level value corresponding to the next actual measurement.
4. The calibration measurement method for a capacitance level meter according to claim 1, characterized in that: The measuring method further comprises: Obtaining the actual capacitance value of the capacitance level meter when actually measuring the level value; The capacity value interval in which the actual capacity value is located is determined, and the actual level value is output based on the corresponding relationship between the capacity value and the level value in the capacity value interval.
5. The calibration measurement method for a capacitance level meter according to claim 4, characterized in that: The measuring method further includes: determining whether the actual capacitance value is within a measuring range; if not, correcting or reporting an error for the actual capacitance value.
6. The calibration measurement method for a capacitance level meter according to claim 5, characterized in that: The measurement method further includes determining the measurement range based on the range of the reference capacitance value.
7. The calibration measurement method for a capacitance level meter according to claim 4, characterized in that: The measurement method further includes: when obtaining the actual capacitance value, performing low-pass filtering on the capacitance sampling signal generated by the capacitance level meter.
8. The calibration measurement method for a capacitance level meter according to claim 1, characterized in that: The lengths of the respective tolerance intervals are equal.
9. A measurement module for a capacitance level meter, characterized in that: include: at least one processor; as well as A memory storing instructions, wherein when the instructions are executed by the at least one processor, the at least one processor executes the calibration measurement method for a capacitance level meter according to any one of claims 1 to 8.
10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores executable instructions, which, when executed, enable the computer to execute the calibration measurement method for a capacitance level meter according to any one of claims 1 to 8.