A method for improving the read-write success rate of RFID printer labels

Abstract

The application discloses a method for improving the reading and writing success rate of RFID printer labels, and belongs to the field of radio frequency identification technology. The method comprises a calibration stage and a reading and writing stage. The calibration stage comprises: moving an RFID sample label and performing step-by-step radio frequency scanning in the length direction of the RFID sample label, and recording the readability state of each discrete position point; identifying a set composed of adjacent readable points based on the state; determining a readable interval based on the length range covered by each set; and determining at least one reading and writing point in each readable interval, so that the total number of the cumulative determined reading and writing points is not less than two. The reading and writing stage comprises: sequentially driving target RFID labels of the same type to each reading and writing point and attempting to read and write, until a reading and writing attempt succeeds; and determining that the label reading and writing fails only when all attempts fail. The application determines multiple reading and writing points in the calibration stage, introduces a sequential fault tolerance mechanism in the reading and writing stage, improves the reading and writing success rate of the labels, and reduces the label loss.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency identification technology, specifically relating to a method for improving the success rate of tag reading and writing in RFID printers. Background Technology

[0002] RFID (Radio Frequency Identification) technology has been widely used in logistics, retail, and asset management. As a key device for integrating label visual information printing and chip data encoding, RFID printers typically require label consumables to be calibrated before performing batch reading and writing to determine their optimal reading and writing positions and operating parameters.

[0003] In existing technologies, tag calibration schemes typically employ a "single-point calibration" mode. Specifically, during the calibration process, only one optimal read / write point location is determined through scanning. Subsequent actual read / write operations on tags of the same model are then performed only at this single, preset point.

[0004] However, this read / write mode, which heavily relies on a single preset location, has inherent drawbacks. First, due to manufacturing tolerances of RFID tag antennas, fluctuations in substrate characteristics, or microscopic inconsistencies during production, the electromagnetic response characteristics of individual tags within the same roll or even the same batch may differ. Second, localized wrinkles, indentations, or minor damage that may occur during transportation, storage, or subsequent processing can also alter the read / write performance of localized areas. These factors can all lead to discrepancies in the readability and writability of critical locations between the sample tags used in the calibration phase and some actually used tags. When this single preset read / write point happens to be located in a weak or defective area of ​​such a tag, the read / write operation will fail. The system will typically determine that the tag is unusable and discard it, which not only reduces the read / write success rate but also results in tag wear and cost waste. Summary of the Invention

[0005] The purpose of this invention is to provide a method that includes an RFID tag calibration stage and an RFID tag read / write stage. In this method, the RFID tag calibration stage not only determines a preferred read / write point, but also intelligently identifies and records at least one backup read / write point. Thus, when the preferred read / write point fails during the read / write stage, the system can switch to the backup read / write point for fault-tolerant attempts, greatly improving the system's robustness to individual tag differences.

[0006] In a first aspect, embodiments of the present invention provide a method for improving the success rate of tag reading and writing in an RFID printer, comprising: During the RFID tag calibration phase, the RFID printer is controlled to move the RFID sample tag, and radio frequency readings are performed at multiple discrete locations along the length of the RFID sample tag during the movement, recording the readability status of each location. Based on the recorded readability status, a set of adjacent discrete location points whose readability status is readable is identified. For each identified set, a readable interval is determined based on the length range covered by the set; within at least one readable interval, at least one physical location is determined as a read / write point, such that the total number of determined read / write points is not less than two. During the RFID tag reading and writing phase, the target RFID tag is driven sequentially to the designated reading and writing points and attempts to read and write until the reading and writing operation is successfully completed in one attempt; the target RFID tag reading and writing is determined to have failed only if all attempts at the designated reading and writing points have failed; the model of the target RFID tag is the same as the model of the RFID sample tag.

[0007] Optionally, the step of performing radio frequency readings at multiple discrete locations along the length of the RFID sample tag and recording the readability status of each location includes: For any target location among the plurality of discrete location points, at that target location point, the reader is controlled to transmit an radio frequency signal; if a response is received from the RFID sample tag within a predetermined time, and valid tag identification information is parsed from the response, the readability status of the target location point is recorded as readable; otherwise, the readability status of the target location point is recorded as unreadable; wherein, the valid tag identification information includes the TID code, EPC code, or specific data code pre-stored in the user storage area of ​​the RFID sample tag; For each identified set, a readable interval is determined based on the length range covered by the set, including: For each identified set, the physical location corresponding to the position with the smallest index in the set is determined as the starting position; the physical location corresponding to the position with the largest index in the set is determined as the ending position; and a readable interval is determined by the starting position and the ending position.

[0008] Optionally, when the number of identified sets is multiple, determining at least one physical location as a read / write point within at least one readable interval includes: For each readable interval, a metric characterizing the readability strength of the readable interval is calculated; The readable intervals are sorted according to the magnitude of the metric value; The midpoint of the readable interval with the largest metric value is determined as the first read / write point; The midpoint of the readable interval with the second largest metric value is determined as the second read / write point.

[0009] Optionally, if the readability status of the target location is recorded as readable, the radio frequency signal strength of the target location is also recorded simultaneously. For each readable interval, the calculation of a metric characterizing the readability strength of the readable interval includes: For each readable interval, calculate the average radio frequency signal strength at all locations within the readable interval; The average radio frequency signal strength is determined as a metric characterizing the readability strength of the readable range.

[0010] Optionally, for each readable interval, calculating a metric characterizing the readability strength of the readable interval includes: For each readable interval, a two-dimensional coordinate system is constructed with the length direction as the horizontal axis and the values ​​of the readability information of each position point within the readable interval as the vertical axis. In the coordinate system, the coordinate points corresponding to consecutive position points within the readable interval are connected to form a polyline; Calculate the area of ​​the region enclosed by the polyline and the horizontal axis, and use this area value as the metric value of the readable interval.

[0011] Optionally, the identified set is the set of all discrete location points that are adjacent and whose readability states are all readable.

[0012] Optionally, when the number of identified sets is one, at least two physical locations are determined as read / write points within the readable region, including: The midpoint of the readable range is defined as the first read / write point; Within the readable range, a physical location at a predetermined distance from the first read / write point is selected as the second read / write point.

[0013] Optionally, the step of sequentially driving the target RFID tag to the determined read / write point and attempting to read / write includes: Drive the target RFID tag to the first read / write point and perform the first read / write attempt; If the first read / write attempt fails, the target RFID tag is driven to the second read / write point and a second read / write attempt is made.

[0014] Secondly, embodiments of the present invention also provide an RFID tag calibration device, which uses the method described in the first aspect for improving the tag reading and writing success rate of RFID printers to calibrate RFID tags. When the target RFID tag is determined to have failed to be read or written, the RFID printer is controlled to print an error mark on the surface of the target RFID tag using thermal transfer or thermal printing.

[0015] Thirdly, embodiments of the present invention also provide a printer, which acquires at least two read / write points determined based on RFID sample tags during the RFID tag calibration phase; and during the RFID tag read / write phase, drives the target RFID tag sequentially to the determined read / write points and attempts to read / write until the read / write operation is successfully completed in one attempt; the target RFID tag is determined to have failed to read / write only if all attempts at the determined read / write points fail; the model of the target RFID tag is the same as the model of the RFID sample tag.

[0016] The technical solution provided in this invention constructs a built-in fault-tolerance mechanism by systematically identifying and recording at least two valid read / write points during the calibration phase. During actual read / write operations, if the first-choice point fails, the system can automatically switch to a backup point for another attempt. This "multi-point backup, sequential attempt" strategy greatly alleviates the absolute dependence on a single physical location, enabling the system to effectively cope with local anomalies in tags, thereby significantly improving the read / write success rate and enhancing the system's robustness and stability. Furthermore, it can significantly reduce the tag rejection rate caused by misjudgments.

[0017] Furthermore, even for the same type of tag, the optimal antenna performance point may vary slightly between different production batches and products from different manufacturers. The calibration method in this embodiment, through a comprehensive scan along the length direction, can adaptively capture the actual effective area distribution of the current sample tag and set multiple read / write points accordingly. This allows RFID printers to no longer rely on a fixed set of parameters, but rather to more flexibly adapt to tag consumables from different sources, reducing the stringent requirements for tag manufacturing consistency and thus improving the overall compatibility and application flexibility of RFID printers. Attached Figure Description

[0018] Figure 1 A flowchart illustrating a method for improving the success rate of tag reading and writing in an RFID printer, as provided in an embodiment of the present invention; Figure 2 A flowchart of a fault-tolerant RFID tag reading and writing method provided in an embodiment of the present invention; Figure 3(a) is a schematic diagram of the readable range and read / write point of an RFID tag in the case of only one readable area provided by an embodiment of the present invention; Figure 3(b) is a schematic diagram of the readable range and read / write point of an RFID tag in the case where there are only two independent readable areas, as provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and technical effects of this invention clearer, the method for improving the success rate of RFID printer tag reading and writing will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of this invention.

[0020] The core of this invention lies in providing a method that includes an RFID tag calibration stage and an RFID tag read / write stage. In this method, the RFID tag calibration stage not only determines a preferred read / write point but also intelligently identifies and records at least one backup read / write point. Therefore, when the preferred read / write point fails during the read / write stage, the system can switch to the backup read / write point for fault-tolerant attempts, greatly improving the system's robustness to individual tag differences.

[0021] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for improving the success rate of tag reading and writing in an RFID printer, which may include the following steps: S110, during the RFID tag calibration stage, controls the RFID printer to move the RFID sample tag, and during the movement, performs radio frequency readings at multiple discrete locations along the length of the RFID sample tag, recording the readability status of each location.

[0022] Specifically, because the antennas of RFID tags (usually etched or printed coils) are distributed along their length, and the coupling strength with the reader antenna may vary at different locations, the readability of RFID tags along their length is not uniform. To systematically detect and record this characteristic, it is necessary to scan along the length by moving the tag.

[0023] Therefore, during the RFID tag calibration phase, the RFID sample tag to be calibrated is installed on the RFID printer, and the printer is controlled to drive the sample tag to move in steps along its length, where the step size is a preset value (e.g., 0.5 mm or 1 mm). During the movement, at multiple predetermined and discrete locations along the tag's length, the printer's reader antenna transmits radio frequency signals to attempt to read the tag.

[0024] For each discrete location, record the readability status of that location based on the result of the read attempt. If a response from the tag is successfully read at that discrete location, such as detecting a valid signal or data, the readability status of that discrete location is recorded as readable; if reading the tag's response fails at that discrete location, the readability status of that discrete location is recorded as unreadable.

[0025] S120, based on the recorded readability states, identifies a set of adjacent discrete location points whose readability states are all readable.

[0026] After scanning and recording multiple discrete location points, an analysis is performed based on all recorded readability states. Sets are identified along the length direction consisting of adjacent discrete location points, all of which have a readable state. Each such set represents a group of sampling points corresponding to a physically continuous, successfully readable region.

[0027] In actual calibration, the number of such sets identified may fall into one of the following two categories: The first case is a single set. Specifically, there is only one continuous readable region along the entire length of the tag, therefore, only one set is identified.

[0028] The second scenario involves multiple sets. Specifically, there are multiple independent, consecutive readable regions separated by unreadable regions along the length of the tag. Therefore, two or more sets will be identified.

[0029] Regardless of whether there is one or more sets, each set will be processed independently for the subsequent definition of the corresponding readable range.

[0030] Furthermore, as a preferred implementation of this invention, when multiple sets are identified, the identified sets can be: all sets consisting of adjacent discrete location points whose readability is readable. This helps in subsequent steps to determine a readable interval for each identified set based on the length range covered by that set, thereby determining multiple readable intervals. Read / write points can then be determined within each of these multiple readable intervals, further improving tag read / write success rate and tag utilization.

[0031] S130, for each identified set, a readable interval is determined based on the length range covered by the set; within at least one readable interval, at least one physical location is determined as a read / write point, such that the total number of determined read / write points is not less than two.

[0032] Each set of continuously readable points corresponds to a potentially valid readable / write region on the sample label. To physically represent these regions, the discrete set of points needs to be mapped to continuous intervals.

[0033] In a preferred embodiment, the start and end boundaries of the readable interval are directly defined by the physical coordinates of the points at the very beginning and the very end of the set in the length direction (i.e., the points with the smallest and largest indices), respectively. For example, if a set consists of consecutive readable points with indices 5 to 12, then the physical position corresponding to the point with index 5 (e.g., 10.0 mm from the label's starting point) is determined as the start position of the readable interval, and the physical position corresponding to the point with index 12 (e.g., 24.0 mm from the label's starting point) is determined as the end position of the readable interval. Thus, the physical line segment between the start and end positions is determined as a readable interval corresponding to the set.

[0034] Understandably, determining the readable interval using the position with the smallest and largest index in the set is an intuitive and efficient method. However, in practical applications, those skilled in the art can also use other algorithms based on the positional information of this set to determine the readable interval. The following three methods are listed: The first method can be called the safety boundary method. Specifically, to avoid unstable boundary point signals, the starting position can be set inside the minimum index point (such as the position point with index 6), and the ending position can be set inside the maximum index point (such as the position point with index 11), to ensure that the readable interval is completely within the high reliability region.

[0035] The second method can be called interpolation extrapolation. Specifically, based on the signal strength variation trend of several points near the edge of the set, linear or nonlinear interpolation is used to estimate the theoretical position where the signal strength reaches the readable threshold, and this theoretical position is used as the interval boundary.

[0036] The third method can be called the geometric center extension method. Specifically, first calculate the geometric center of the set, and then extend it to both ends by a fixed or proportional length to cover most of the readable points.

[0037] Regardless of which method is used to determine the readable interval, the core idea is to uniquely define a physically continuous range, i.e., the readable interval, based on the spatial distribution information contained in the set by determining a start position and an end position.

[0038] After determining the readable region using the above method, at least one specific physical location within the readable region must be identified as a read / write point. This ensures that the total number of read / write points identified within the determined readable regions is no less than two. The specific rules for determining the read / write points can be as follows: the midpoint of the readable region can be selected as the primary read / write point, and other internal locations within the readable region can be used as alternative read / write points based on actual needs. In short, the core objective of this step is to ensure that at least two distinct physical locations within the readable region are obtained.

[0039] At this point, the RFID tag calibration phase is complete. Its core output is the location information of multiple preset read / write points, which will be stored and used for subsequent read / write operations on tags of the same model.

[0040] S140, during the RFID tag reading and writing phase, the target RFID tag is driven sequentially to the determined reading and writing points and attempts to read and write until the reading and writing operation is successfully completed in one attempt; the target RFID tag reading and writing is determined to have failed only if all attempts at the determined reading and writing points have failed.

[0041] The target RFID tag has the same model number as the RFID sample tag.

[0042] When it is necessary to perform read / write operations such as writing data to the target RFID tag, first confirm that the model of the target RFID tag is the same as the model of the RFID sample tag used during calibration.

[0043] Then, execute the fault-tolerant read / write process, such as... Figure 2 As shown, it may include the following steps: S151, move the target RFID tag to the first read / write point among the multiple read / write points determined in the above calibration phase, and attempt to perform read / write operations at this location.

[0044] The control system selects the first or highest priority read / write point from the set of read / write points generated and stored during the calibration phase as the target location for the first attempt. Subsequently, the drive tag delivery mechanism precisely moves the target RFID tag so that the target location is aligned with the effective area of ​​the reader antenna's radio frequency field.

[0045] Once the tag is located, the control unit instructs the RF module to initiate a complete read / write transaction at that location, attempting to write data. This step aims to prioritize the location with the highest probability of success identified during the calibration phase, maximizing the success rate of the first attempt.

[0046] S152, If the read / write operation is successfully completed in this attempt, the process ends.

[0047] Specifically, if the read / write attempt is successful, that is, the reader successfully establishes communication with the target tag at the current location, writes the predetermined data (such as EPC code, user data, etc.) completely into the non-volatile memory of the tag chip, and then confirms through a post-read verification operation that the written data is completely consistent with the source data and passes the verification, then the read / write task for the target RFID tag is considered to have been successfully completed.

[0048] S153, If this attempt fails, move the target label to the next read / write point and try reading / writing again. Repeat this step, trying at each read / write point in turn.

[0049] S154, until a read / write operation is successfully completed in one attempt.

[0050] If the first attempt in step S151 fails, for example, if no valid response is received within the predetermined time or verification fails, the fault tolerance mechanism is activated. The control system moves the target tag to the next read / write point (i.e., the second read / write point) among the plurality of read / write points, and re-initiates a complete read / write attempt at this new location.

[0051] If the attempt at the second read / write point still fails, repeat the logic of step S153, moving the target RFID tag to a subsequent read / write point (such as the third or fourth read / write point), and attempting it sequentially at each new point. This iterative process continues until a read / write operation is successfully completed at a certain read / write point, thus satisfying the success condition described in step S152.

[0052] S155: The system will only determine that the target RFID tag has failed to read or write if all attempts have been made at all read / write points and all attempts have failed.

[0053] The system will only determine that the target RFID tag has failed to read or write if the target RFID tag has made complete read / write attempts at all preset read / write points (i.e., the first read / write point and all subsequent alternative read / write points) and all attempts have failed.

[0054] As one implementation of the present invention, when it is determined that the target RFID tag has failed to be read or written, the RFID printer is controlled to print an error mark on the surface of the target RFID tag by means of thermal transfer or thermal printing.

[0055] Specifically, after determining that the target RFID tag has failed to read or write, a predefined error mark is printed on the visible surface area of ​​the target RFID tag (usually the printed surface of the tag) using thermal transfer or thermal printing.

[0056] Error markers can be specific text, such as "ERROR", "FAIL", "Invalid", or a custom error code. Error markers can also be specific graphics, such as an X, an exclamation mark "!", or a specific color block or barcode. Of course, error markers can also be a combination of specific text and specific graphics, which is also acceptable.

[0057] Printing error markings provides direct visual evidence for subsequent automated sorting or manual inspection, facilitating the rapid separation of defective labels from qualified products. Furthermore, it prevents failed labels from being mistakenly affixed or misused due to a lack of visual distinction, ensuring consistency between data and physical entities.

[0058] The technical solution provided in this invention constructs a built-in fault-tolerance mechanism by systematically identifying and recording at least two valid read / write points during the calibration phase. During actual read / write operations, if the first-choice point fails, the system can automatically switch to a backup point for another attempt. This "multi-point backup, sequential attempt" strategy greatly alleviates the absolute dependence on a single physical location, enabling the system to effectively cope with local anomalies in tags, thereby significantly improving the read / write success rate and enhancing the system's robustness and stability. Furthermore, it can significantly reduce the tag rejection rate caused by misjudgments.

[0059] Furthermore, even for the same type of tag, the optimal antenna performance point may vary slightly between different production batches and products from different manufacturers. The calibration method in this embodiment, through a comprehensive scan along the length direction, can adaptively capture the actual effective area distribution of the current sample tag and set multiple read / write points accordingly. This allows RFID printers to no longer rely on a fixed set of parameters, but rather to more flexibly adapt to tag consumables from different sources, reducing the stringent requirements for tag manufacturing consistency and thus improving the overall compatibility and application flexibility of RFID printers.

[0060] Based on the above embodiments, as one implementation of the present invention, radio frequency reading is performed at multiple discrete locations along the length of the RFID sample tag, and the readability status of each location is recorded. This can be achieved through the following specific steps: Step a1: For any target location among multiple discrete location points, control the reader to transmit an radio frequency signal at the target location point.

[0061] Once the RFID sample tag moves to a predetermined discrete location (called the target location point) and stabilizes under the drive of the control system, the control unit instructs the reader's radio frequency module to transmit a radio frequency signal conforming to the communication protocol at the target location point.

[0062] Step a2: If a response is received from the RFID sample tag within the predetermined time and valid tag identification information is parsed from the response, the readability status of the target location point is recorded as readable; otherwise, the readability status of the target location point is recorded as unreadable.

[0063] Among them, valid tag identification information includes the TID code, EPC code, or specific data code pre-stored in the user's storage area of ​​the RFID sample tag.

[0064] The reader continuously listens for responses from RFID sample tags within a predetermined time window (e.g., a few milliseconds to tens of milliseconds) after transmitting a signal. If a valid radio frequency response is received within the predetermined time, and the decoder successfully extracts valid identification information uniquely identifying the tag from the response signal, the tag is determined to be readable at the target location. The readability status of the target location is recorded as readable. Valid tag identification information includes, but is not limited to: 1. TID code: The unique identification code of the tag itself, which is fixed by the chip manufacturer.

[0065] 2. EPC code: Electronic product code, stored in the user-programmable storage area of ​​the tag.

[0066] 3. Specific data code in the user storage area: Known data that the user has pre-written into a specific storage block labeled with a tag.

[0067] If no response is received within the predetermined time, or the received response cannot be decoded, or the decoded information is not valid tag identification information, the tag at the target location point is determined to be unreadable, and the readability status of the target location point is recorded as unreadable.

[0068] Furthermore, after recording the readability status of the target location, the RFID sample tag is driven to the next discrete location, and steps a1 and a2 are repeated until all predetermined discrete location points along the length direction are traversed, thereby obtaining a complete readability status sequence consisting of "readable" and "unreadable" states. This sequence objectively characterizes the radio frequency response characteristics of the sample tag along the length direction.

[0069] This embodiment achieves fully automated and highly reliable acquisition of readability status by using protocol responses and multi-type tag identification information (TID / EPC / user data) as objective judgment criteria. This design not only ensures the accuracy and consistency of the calibration data source, providing reliable input for subsequent algorithms, but also significantly improves the versatility of the technical solution and its adaptability to different application scenarios and tag types due to its broad compatibility with various identification information, thereby enhancing the robustness and deployment flexibility of the RFID printer calibration and reading / writing system.

[0070] Furthermore, during the actual calibration process, the number of consecutive readable point sets identified may fall into two categories: a single set or multiple independent sets. This embodiment will focus on the case where multiple sets are identified, and will elaborate in detail on how to determine multiple read / write points within the readable intervals corresponding to these sets.

[0071] As one implementation of this invention, when there are multiple identified sets, determining at least one physical location as a read / write point within at least one readable interval may include the following steps: Step b1: For each readable interval, calculate a metric that characterizes the readability strength of the readable interval.

[0072] For each readable interval defined by the set, a metric is calculated that quantifies the overall readability of that interval. This metric is a comprehensive evaluation of the readability performance of all points within the interval.

[0073] Step b2: Sort the readable intervals according to the size of the metric value.

[0074] Based on the metric calculated in step b1, all readable intervals are sorted from largest to smallest to determine the priority of each interval in terms of readability.

[0075] Step b3: Determine the midpoint of the readable interval with the largest metric value as the first read / write point.

[0076] Select the readable interval with the largest metric value, that is, the area that is determined to be the strongest or most stable signal, calculate the physical coordinates of the midpoint of the interval, and determine this coordinate position as the first read / write point.

[0077] Step b4: Determine the midpoint of the readable interval with the second largest metric value as the second read / write point.

[0078] Select the readable interval with the second largest metric value, calculate the physical coordinates of the midpoint of this interval, and determine this coordinate position as the second read / write point.

[0079] Through the above steps, the system can intelligently select the best and second-best readable intervals from multiple valid readable regions, and use the center point of the best readable interval as the primary read / write point (i.e., the first read / write point), and the center point of the second-best readable interval as the alternative read / write point (i.e., the second read / write point), laying the foundation for subsequent fault-tolerant operations.

[0080] Furthermore, since the first and second read / write points are located in different readable regions, and these readable regions are physically separated by unreadable areas, sufficient distance is ensured between the two read / write points. This setup effectively avoids potential radio frequency signal interference caused by read / write points being too close together, thereby further ensuring the independence and success rate of read / write attempts at each read / write point.

[0081] As a preferred implementation, if the radio frequency signal strength (RSSI) at each readable location point is recorded synchronously during the calibration scan, then the calculation of the measurement value in step b1 can be specified as follows: Step b11: For each readable interval, calculate the average radio frequency signal strength at all locations within the readable interval.

[0082] Step b12, the average radio frequency signal strength is determined as a metric characterizing the readability strength of the readable range.

[0083] Specifically, for each readable interval, the radio frequency (RF) signal strength values ​​recorded at all locations within the interval are extracted. The arithmetic mean of these signal strength values ​​is calculated, and this average RF signal strength is directly used as a metric characterizing the readability of that readable interval. This method intuitively reflects the average energy level of the signal within the readable interval, is simple to calculate, and has a clear physical meaning.

[0084] As another preferred approach, for each readable section, calculating a metric characterizing the readability strength of the readable section may include the following steps: Step b13: For each readable interval, construct a two-dimensional coordinate system with the length direction as the horizontal axis and the numerical values ​​based on the readability information of each position point within the readable interval as the vertical axis.

[0085] Specifically, for each readable region, a two-dimensional coordinate system is established with the length of the label as the horizontal axis (X-axis) and the readability-related values ​​at each location point as the vertical axis (Y-axis). The vertical axis values ​​can be simple readability status values, such as 1 for readable and 0 for unreadable, or they can be the radio frequency signal strength value at that point.

[0086] Step b14: In a two-dimensional coordinate system, connect the coordinate points corresponding to consecutive position points within the readable interval to form a polyline.

[0087] In this coordinate system, the coordinates of each position point belonging to the readable range and arranged in sequence are connected by line segments to form a broken line.

[0088] Step b15: Calculate the area of ​​the region enclosed by the polyline and the horizontal axis, and use this area value as the measure of the readable interval.

[0089] Specifically, the area of ​​the closed region enclosed by the broken line and the horizontal axis (Y=0) is calculated. This area value is used as the measure of the readable interval. When the vertical axis takes values ​​of 1 and 0, the area value equals the physical length of the interval; when the vertical axis takes the signal strength, the area value reflects the cumulative effect of the signal strength on the readable interval, taking into account both the interval length and the signal strength.

[0090] This "area method" comprehensively considers the length of the interval and the distribution of signal strength through the idea of ​​integration. It is a robust algorithm for selecting the largest and second largest continuous effective readable regions.

[0091] In summary, this embodiment provides a variety of specific technical paths for intelligently selecting primary and backup read / write points from multiple readable intervals. The system can choose a calculation method based on average signal strength or geometric area according to actual needs and the completeness of data acquisition. Both methods can effectively achieve the purpose of optimizing intervals and setting multiple write points, thereby supporting subsequent efficient fault-tolerant read / write processes.

[0092] As one implementation of this invention, when only one set of continuously readable points is identified after calibration scanning (i.e., only one continuous valid readable area exists along the entire length of the tag), "determining at least two physical locations as read / write points within the readable range" can be achieved through the following steps to ensure that at least two read / write points can still be obtained, thus meeting the basic requirements of the fault tolerance mechanism: Step c1: Determine the midpoint of the readable interval as the first read / write point.

[0093] Calculate the coordinates of the midpoint of this unique readable region along its length. Determine the physical location corresponding to this midpoint as the first read / write point. This point is the theoretical center of the continuous readable region and typically has a high probability of successful read / write operations.

[0094] Step c2: Within the readable range, select a physical location at a predetermined distance from the first read / write point as the second read / write point.

[0095] Within the single readable zone, a physical location at a predetermined distance from the first read / write point is selected as the second read / write point. Specifically, this predetermined distance is typically set along the label's transport direction (i.e., the length direction). Furthermore, this predetermined distance can be a fixed empirical value, such as 2 mm. This empirical value is based on industry experience and is usually less than the minimum length of a typical readable zone to ensure the second point still falls within the effective area. Alternatively, the predetermined distance can be a preset percentage of the readable zone length, for example, 10% or 20% of the zone length. This method can adapt to labels of different sizes.

[0096] Furthermore, the system needs to verify whether the calculated candidate position of the second read / write point is indeed within the range of the readable interval. If the verification passes, it is officially determined as the second read / write point; if the verification fails (for example, the calculated point falls outside the interval), it is adjusted according to preset rules (such as halving the distance or directly taking the interval endpoint) until a valid position within the interval is obtained.

[0097] Through the above steps, even when only one continuous readable area is detected, this solution can still generate two read / write points within the valid area using a "center point + offset point" strategy. This ensures that the fault-tolerant read / write process can still be executed in single-area scenarios. That is, when the attempt at the first read / write point (center point) fails, the system can move to the second read / write point (offset point) to try again, thereby significantly improving the robustness of reading and writing tags with only a single valid read / write area and avoiding the direct scrapping of the entire tag due to the accidental failure of a single read / write point.

[0098] After determining the first and second read / write points for both multiple sets and a single set, the system enters the RFID tag read / write phase. At this point, the target RFID tag is sequentially driven to the read / write point and read / write attempts are performed, forming a complete, automatic, fault-tolerant closed loop: Step d1: Drive the target RFID tag to the first read / write point and make the first read / write attempt.

[0099] Based on stored calibration data, the control system drives the tag delivery mechanism to precisely move the target RFID tag to the first read / write point, aligning this point with the effective radio frequency field of the reader antenna. Subsequently, the control unit instructs the radio frequency module to initiate a complete read / write transaction at that point with optimal or preset power, performing the first read / write attempt. This step aims to prioritize the use of the determined optimal or most stable location to ensure a high success rate for the first operation.

[0100] Step d2: If the first read / write attempt fails, drive the target RFID tag to the second read / write point and attempt a second read / write attempt.

[0101] If the first read / write attempt is successful, the read / write task for the target RFID tag is considered complete, the process terminates, and the tag enters the subsequent processing stage.

[0102] If the first read / write attempt fails, such as not receiving a valid response or failing verification within the predetermined time, the fault tolerance mechanism is immediately triggered. That is, after the first attempt fails, the control system does not immediately determine that the tag read / write has failed, but instead drives the tag away from the first read / write point and moves it to the second read / write point. Similarly, after accurate positioning, the system initiates a second read / write attempt at the second read / write point. If this attempt succeeds, the read / write task is considered complete, and the process ends. If this attempt also fails, it indicates that after attempts at the two optimal read / write points (primary and backup), the tag still cannot be successfully read / written. At this point, the system finally determines that the target RFID tag read / write has failed. Subsequently, follow-up processing operations such as printing an error mark and placing the target RFID tag in a waste bin can be performed.

[0103] The purpose of this embodiment is to link discrete "location determination" with continuous "operation execution" to construct an intelligent decision-making process of "preferred attempt → failure judgment → automatic switching → alternative attempt → final judgment". This process ensures that each tag's read / write operation has undergone at least two independent attempts at different valid physical locations, thereby minimizing the probability of failure due to local accidental factors and systematically achieving the core objectives of this invention: improving read / write success rate and reducing tag wear.

[0104] Based on the above-described scanning calibration and read / write point determination embodiments, as a further optimized implementation of this invention, when performing RF readings at multiple discrete locations, RF power detection and recording can be performed simultaneously to adaptively determine an optimal reference read / write power. This method specifically includes the following steps: Step e1: Record the minimum and maximum radio frequency power used when the RFID sample tag is successfully read.

[0105] Specifically, during the step scanning process of RFID sample tags, whenever a tag is successfully read at a discrete location, not only is its readability status and signal strength recorded, but also the actual radio frequency power value used by the reader during this successful reading process is recorded simultaneously.

[0106] After traversing all discrete location points, the system filters out the minimum and maximum RF power values ​​used from all successful read events. The minimum RF power value represents the lowest energy threshold required to activate the tag, while the maximum RF power value represents the highest power attempted to successfully read the tag within the scanning range.

[0107] Step e2: The intermediate value between the minimum and maximum radio frequency power is determined as the reference read / write power for reading and writing the target RFID tag.

[0108] Based on the recorded minimum and maximum radio frequency power values, a baseline read / write power is determined by calculating the median value between the two for subsequent read / write operations on the same type of target RFID tags.

[0109] This intermediate value selection strategy avoids the risk of read / write instability caused by minor environmental fluctuations or slight differences in individual tags when using the minimum RF power, while also avoiding the energy waste, potential increased co-channel interference, and stress on the tag chip that may result from using the maximum RF power. Choosing the intermediate value ensures a balance between reliability and energy efficiency / compatibility.

[0110] In summary, applying this baseline read / write power to subsequent read / write stages ensures sufficient but not excessive energy for the tag chip in most cases, thereby further improving the stability and success rate of read / write operations. This is particularly effective when dealing with tags from different batches or exhibiting slight performance fluctuations, significantly reducing read / write failures caused by improper power settings. This enhances the robustness and adaptability of the entire method.

[0111] To clearly describe the scheme, the relationship between the readable range and the read / write point will be illustrated from the perspective of the physical tag, using Figures 3(a) and 3(b).

[0112] It should be noted that the aforementioned readable range refers to a continuous range (one-dimensional line segment) along the length of the label. In Figures 3(a) and 3(b), a gray rectangular area with width is used to illustrate this range and its position on the label. Those skilled in the art should understand that the span of this gray area along its length corresponds to the readable range of the above embodiment, and its width is shown only for clarity and is not intended to limit the invention.

[0113] Please refer to Figure 3(a). For clarity, a gray rectangular area is used in the figure to represent the continuous readable range on the RFID tag. Those skilled in the art will understand that the span of this gray area in the length direction (horizontal direction in the figure) corresponds to the one-dimensional readable interval defined by the method of the present invention.

[0114] After performing a calibration scan and recording the readability status of each discrete location point, the system identifies only one set consisting of consecutive readable points. This set corresponds to a continuous valid range along the length of the tag. Based on the length range covered by this set, the system determines a unique readable interval, namely the length range indicated by the gray area in Figure 3(a).

[0115] Subsequently, two read / write points are determined within this readable interval (the length range of this segment), and the specific steps are as follows: 1. Determine the first read / write point (midpoint of the interval): Calculate the coordinates of the midpoint of the readable interval along its length. Determine the physical location corresponding to this midpoint as the first read / write point. This point is located at the center of the effective range of this segment.

[0116] 2. Determine the second read / write point (offset point within the interval): To provide fault tolerance, a backup point needs to be set within the same effective length range. Using the first read / write point as a reference, the system offsets along the length direction by a predetermined distance to calculate another physical location as a candidate point. The system verifies whether the length coordinates of this candidate point are still within the readable interval (the length range of this segment). If the verification passes, it is determined as the second read / write point.

[0117] Next, the read / write phase begins. The target tag is moved to the first read / write point, and a read / write operation is attempted. If the first read / write attempt is successful, the process ends, and the tag processing is complete. If the first read / write attempt fails, the target tag is moved to the second read / write point, and the read / write operation is retried.

[0118] If the read / write attempt at the second read / write point is successful, the read / write task is completed; if the attempt at the second read / write point also fails, the read / write of the tag is ultimately determined to have failed, and subsequent processing such as printing an error mark can be performed.

[0119] This embodiment solves the problem that traditional solutions render tags unusable due to a single point of failure when a tag has only one effective area. By intelligently setting the first and second read / write points within the same reliable area, basic fault tolerance is successfully built without adding any extra hardware or relying on other areas. This significantly improves the read / write success rate for such tags and reduces losses, making it particularly suitable for tag models with compact antenna designs or a single effective area, demonstrating the completeness and universality of the method of this invention.

[0120] Please refer to Figure 3(b). For clarity, two independent gray rectangular areas are used in the figure to represent two independent continuous readable ranges along the length of the RFID tag. Those skilled in the art will understand that the span of each of these two gray areas along the length direction (horizontal direction in the figure) corresponds to the two independent readable intervals defined by the method of the present invention.

[0121] After performing a calibration scan and recording the readability status of each discrete location point, the system identifies two sets consisting of consecutive readable points. Each set corresponds to an independent, continuous, valid range along the length of the tag. Based on the length range covered by each set, the system determines two independent readable intervals, namely, the first readable interval and the second readable interval, which are two gray areas in 3(b).

[0122] Subsequently, at least one read / write point is determined for each readable interval, and the best one is selected based on the metric value. The specific steps are as follows: The first step is to calculate the metric for each readable interval.

[0123] To intelligently select the first and second readable points from two valid intervals, they need to be quantitatively evaluated. This embodiment provides two preferred methods: Method A: If the signal strength is recorded during the calibration process, calculate the average radio frequency signal strength at all locations within each readable interval and use this average value as the metric for that interval.

[0124] Method B: As described in the previous embodiments, a line graph is constructed with length as the horizontal axis and readability-related values ​​as the vertical axis, and the area under the line graph corresponding to each readable interval is calculated as its metric. This area value comprehensively reflects the cumulative effect of the interval's length and signal strength (or readability).

[0125] The second step is to sort the data according to the metrics and determine the read / write points.

[0126] 1. Compare the metrics of the two readable intervals. The interval with the largest metric value is determined as the preferred readable interval (usually corresponding to the longer gray area in 3(b), i.e., the first readable interval), and the interval with the second largest metric value is determined as the alternative readable interval (usually corresponding to the shorter gray area in 3(b), i.e., the second readable interval).

[0127] 2. Determine the first read / write point: Calculate the coordinates of the midpoint of the first readable interval along its length. Determine the physical location corresponding to this midpoint as the first read / write point.

[0128] 3. Determine the second read / write point: Calculate the coordinates of the midpoint of the second readable interval along its length. Determine the physical location corresponding to this midpoint as the second read / write point.

[0129] The third step, after obtaining the first read / write point and the second read / write point located in two different physical regions, is to execute the following fault-tolerant read / write process: First, move the target tag to the first read / write point and attempt a read / write operation. If the attempt at the first read / write point is successful, the process ends. If the attempt at the first read / write point fails, the fault tolerance mechanism is activated. Move the target RFID tag to the second read / write point and attempt to read / write again.

[0130] If the attempt at the second read / write point is successful, the task is completed; if the attempt at the second read / write point also fails, the tag read / write is ultimately determined to have failed.

[0131] This invention fully utilizes multiple independent and effective areas on the tag. Through intelligent decision-making via "metric calculation-sorting optimization," the system can automatically identify the primary and backup readable areas with the most stable and reliable signal from multiple areas, and set their center points as read / write points. This not only provides stronger fault tolerance with complete physical isolation but also ensures that the primary and backup point settings are optimal. This solution is suitable for tags with complex antenna designs or uneven signal distribution, maximizing the exploitation and utilization of the tag's own physical characteristics, thereby improving the tag read / write success rate.

[0132] This invention also provides an RFID tag calibration device, which uses the method described in the above embodiments to improve the success rate of RFID printer tag reading and writing for RFID tag calibration; When the target RFID tag is determined to have failed to be read or written, the RFID printer is controlled to print an error mark on the surface of the target RFID tag using thermal transfer or thermal printing.

[0133] It should be noted that the working principle of the RFID tag calibration device embodiment is similar to that of the aforementioned method embodiment, and will not be repeated here.

[0134] The RFID tag calibration device provided in this invention, by applying the aforementioned method, can not only systematically determine multiple optimal read / write points to improve the error tolerance and accuracy of calibration, but also automatically print clear error marks on the surface of tags when they are ultimately determined to be unqualified. This function realizes the immediate physical identification and isolation of defective tags, effectively preventing their misuse or mixing with qualified products in subsequent stages, completing closed-loop management from "intelligent detection" to "automatic handling," and improving the automation and reliability of the production process.

[0135] This invention also provides a printer that acquires at least two read / write points determined based on RFID sample tags during the RFID tag calibration phase; and during the RFID tag read / write phase, drives the target RFID tag sequentially to the determined read / write points and attempts to read / write until a read / write operation is successfully completed in one attempt; the target RFID tag is determined to have failed to read / write only if all attempts at the determined read / write points have failed; the model of the target RFID tag is the same as the model of the RFID sample tag.

[0136] It should be noted that the working principle of the printer is similar to that of the aforementioned method embodiments, and will not be repeated here.

[0137] The printer provided in this invention offers a highly integrated overall solution by directly integrating and executing the complete process of the aforementioned method. Users do not need to configure separate calibration and printing devices, simplifying the system architecture and operation process, and reducing overall costs. Simultaneously, this integrated design ensures consistency in strategies from calibration to reading and writing, avoiding performance losses due to differences between devices. It allows redundant reading and writing and fault-tolerance mechanisms to operate seamlessly and efficiently within a single device, greatly guaranteeing the final label reading and writing success rate and production continuity.

Claims

1. A method for improving the success rate of tag reading and writing in RFID printers, characterized in that, include: During the RFID tag calibration phase, the RFID printer is controlled to move the RFID sample tag, and radio frequency readings are performed at multiple discrete locations along the length of the RFID sample tag during the movement, recording the readability status of each location. Based on the recorded readability status, a set of adjacent discrete location points whose readability status is readable is identified. For each identified set, a readable interval is determined based on the length range covered by the set; within at least one readable interval, at least one physical location is determined as a read / write point, such that the total number of determined read / write points is not less than two. During the RFID tag reading and writing phase, the target RFID tag is driven sequentially to the designated reading and writing points and attempts to read and write until the reading and writing operation is successfully completed in one attempt; the target RFID tag reading and writing is determined to have failed only if all attempts at the designated reading and writing points have failed; the model of the target RFID tag is the same as the model of the RFID sample tag.

2. The method according to claim 1, characterized in that, The step of performing radio frequency readings at multiple discrete locations along the length of the RFID sample tag and recording the readability status of each location includes: For any target location among the plurality of discrete location points, at that target location point, the reader is controlled to transmit an radio frequency signal; if a response is received from the RFID sample tag within a predetermined time, and valid tag identification information is parsed from the response, the readability status of the target location point is recorded as readable; otherwise, the readability status of the target location point is recorded as unreadable; wherein, the valid tag identification information includes the TID code, EPC code, or specific data code pre-stored in the user storage area of ​​the RFID sample tag; For each identified set, a readable interval is determined based on the length range covered by the set, including: For each identified set, the physical location corresponding to the position with the smallest index in the set is determined as the starting position; the physical location corresponding to the position with the largest index in the set is determined as the ending position; and a readable interval is determined by the starting position and the ending position.

3. The method according to claim 1, characterized in that, When there are multiple identified sets, determining at least one physical location as a read / write point within at least one readable interval includes: For each readable interval, a metric characterizing the readability strength of the readable interval is calculated; The readable intervals are sorted according to the magnitude of the metric value; The midpoint of the readable interval with the largest metric value is determined as the first read / write point; The midpoint of the readable interval with the second largest metric value is determined as the second read / write point.

4. The method according to claim 3, characterized in that, If the readability status of the target location is recorded as readable, the radio frequency signal strength of the target location is also recorded simultaneously. For each readable interval, the calculation of a metric characterizing the readability strength of the readable interval includes: For each readable interval, calculate the average radio frequency signal strength at all locations within the readable interval; The average radio frequency signal strength is determined as a metric characterizing the readability strength of the readable range.

5. The method according to claim 3, characterized in that, For each readable interval, the calculation of a metric characterizing the readability strength of the readable interval includes: For each readable interval, a two-dimensional coordinate system is constructed with the length direction as the horizontal axis and the values ​​of the readability information of each position point within the readable interval as the vertical axis. In the coordinate system, the coordinate points corresponding to consecutive position points within the readable interval are connected to form a polyline; Calculate the area of ​​the region enclosed by the polyline and the horizontal axis, and use this area value as the metric value of the readable interval.

6. The method according to claim 3, characterized in that, The identified set is the set of all discrete locations that are adjacent and whose readability is readable.

7. The method according to claim 1, characterized in that, When the number of identified sets is one, at least two physical locations are determined as read / write points within the readable region, including: The midpoint of the readable range is defined as the first read / write point; Within the readable range, a physical location at a predetermined distance from the first read / write point is selected as the second read / write point.

8. The method according to claim 3 or 7, characterized in that, The step of sequentially driving the target RFID tag to the determined read / write point and attempting to read / write includes: Drive the target RFID tag to the first read / write point and perform the first read / write attempt; If the first read / write attempt fails, the target RFID tag is driven to the second read / write point and a second read / write attempt is made.

9. An RFID tag calibration device, characterized in that, RFID tag calibration is performed using the method for improving the success rate of RFID printer tag reading and writing as described in any one of claims 1 to 8; When the target RFID tag is determined to have failed to be read or written, the RFID printer is controlled to print an error mark on the surface of the target RFID tag using thermal transfer or thermal printing.

10. A printer, characterized in that, The printer acquires at least two read / write points determined based on the RFID sample tag during the RFID tag calibration phase; and during the RFID tag read / write phase, it sequentially drives the target RFID tag to the determined read / write points and attempts to read / write until the read / write operation is successfully completed in one attempt; the target RFID tag is determined to have failed to read / write only if all attempts at the determined read / write points fail; the model of the target RFID tag is the same as the model of the RFID sample tag.

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