Transparent bottle and bag product removing method and system based on label existence detection

Abstract

The invention relates to the technical field of automatic detection and removal, in particular to a transparent bottle and bag product removal method and system based on label existence detection, and the system comprises a diffuse reflection photoelectric switch, an annular fluorescence detection sensor array, a PLC (Programmable Logic Controller) and a removal cylinder. A label existence matrix is constructed and a coverage integrity index is calculated through multi-angle ultraviolet excitation and signal acquisition by utilizing the difference between the fluorescence characteristic of the label and the non-fluorescence response of a bottle body, so that label missing or damage is judged, accurate elimination and alarm are triggered, and meanwhile, an abnormal event is recorded for tracing. According to the method, the transparent bottle and bag products without labels or with abnormal labels can be efficiently and reliably recognized and removed, wrong removal is avoided, and the quality control level of a production line is improved.

Description

Technical Field

[0001] This invention belongs to the field of industrial automation and machine vision inspection technology, specifically a method and system for rejecting transparent bottle and bag products based on label presence detection. Background Technology

[0002] In the automated production process of transparent bottle and bag products, to ensure product traceability and compliance, paper labels are typically affixed to the product surface to indicate key information such as product name, ingredients, and production date. "Bottle" refers to a container with a cylindrical body, while "bag" refers to flat, flexible packaging. However, in actual production, due to labeling equipment malfunctions, label detachment, or scratches during transportation, some products may be unlabeled or have missing labels. If such unlabeled products enter the market, they can easily trigger consumer complaints and even recalls, seriously affecting the company's reputation and the effectiveness of its product quality control system.

[0003] Currently, the industry commonly uses machine vision-based inspection solutions, which involve taking pictures of products with industrial cameras and using image processing algorithms to compare them with standard templates to identify the presence of labels. While this method achieves a degree of automation, it still has significant drawbacks: First, the system requires high-resolution cameras, image acquisition cards, and dedicated industrial control computers, resulting in high overall costs and hindering its widespread application in small and medium-sized production lines. Second, for cylindrical bottle products, random rotation on the conveyor line can cause uncertain label orientation, and the camera may be unable to stably capture the label area due to obstructed viewpoints or glare, leading to misjudgments (incorrectly rejecting labeled products) or missed judgments (failing to reject unlabeled products), severely impacting the reliability and stability of the inspection.

[0004] Therefore, there is an urgent need for a low-cost, interference-resistant, and label presence detection method applicable to transparent bottle and bag products of different shapes (especially cylindrical bottles) to overcome the limitations of existing visual inspection technologies in practical applications and improve the quality control level and operating efficiency of the production line. Summary of the Invention

[0005] To address the aforementioned technical problems, the purpose of this application is to provide a method and system for rejecting transparent bottle / bag products based on label presence detection. The specific technical solution adopted is as follows: This application provides a method for rejecting transparent bottle / bag products based on label presence detection, comprising the following steps: A diffuse reflection photoelectric switch and an array of multiple fluorescence detection sensors are installed on the conveyor line. When the transparent bottle / bag product enters the detection station, the diffuse reflection photoelectric switch triggers a detection start signal. Based on the characteristic that the bottle / bag body and its internal liquid do not respond to fluorescence under specific wavelengths of ultraviolet light, while the paper label contains excitable fluorescent material, fluorescence detection sensors arranged at multiple angles are used to penetrate and receive light around the product, acquiring the fluorescence response signal sequence of each sensor. A product label presence confidence matrix is ​​constructed based on the fluorescence response signal sequence. Combining the bottle's geometric parameters and the sensor's spatial layout, a label coverage integrity index is calculated, and the presence of a valid label is determined based on this index. If the product is determined to be without a label or with a missing label, a rejection command is generated and an audible and visual alarm is triggered simultaneously. The rejection instruction drives the rejection cylinder to perform a physical interception action, separating the unqualified products from the conveyor line, and at the same time recording the abnormal event to the PLC log module for quality traceability.

[0006] Preferably, the fluorescence detection sensor array is arranged in a ring shape along the vertical cross-section of the product conveying direction, and its number N satisfies the formula: Where D is the diameter of the cylindrical bottle body. The effective detection width of a single fluorescence detection sensor on the bottle surface. This function rounds up to ensure that the overlap of adjacent sensor detection areas is not less than 15%, thus eliminating detection blind spots caused by bottle rotation.

[0007] Preferably, the label coverage integrity index The calculation method is as follows: ;in, For the first A fluorescence detection sensor at time The output normalized fluorescence intensity signal, To preset the fluorescence response threshold, This is a step function that outputs 1 when the input is greater than 0, and 0 otherwise; this index reflects the proportion of the product circumference covered by the effective label.

[0008] Preferably, the response states of all fluorescence detection sensors within a unit detection cycle are mapped to a binary tag existence matrix according to their spatial location. The element in the k-th column of the matrix indicates whether the k-th sensor has detected the tag fluorescence signal, which is used for subsequent integrity assessment and fault location.

[0009] Preferably, the generation condition for the rejection instruction is: when the tag coverage integrity index... The event is triggered at a specific time, where θ is the integrity threshold, with a value range of 0.3≤θ≤0.6. It is dynamically set according to the minimum allowable area ratio of the label to ensure that only products with truly missing labels are removed, thus avoiding false removals.

[0010] Preferably, the fluorescence detection sensor emits ultraviolet light at a wavelength of 365 nm, and the receiving end is equipped with a bandpass filter with a center wavelength of 450 nm and a half-width at half-maximum (WHM) of ±20 nm to suppress ambient stray light interference and enhance the signal-to-noise ratio of the label fluorescence signal; the bottle / bag material and contents do not exhibit spontaneous fluorescence within this excitation-emission band, ensuring that the background signal remains constant at a low level.

[0011] Preferably, the PLC controller uses a time synchronization mechanism to open a detection window of fixed width after the diffuse reflection photoelectric switch is triggered. Fluorescence signals are sampled only within this window to avoid crosstalk between signals from preceding and following products. satisfy ,in This is the maximum axial length of the product. The diameter of the sensor spot. This refers to the conveyor line speed.

[0012] Preferably, the step of determining whether a valid label exists based on the label coverage integrity index further includes: when When it is judged as a qualified product, it will not trigger rejection; when If the system is determined to be completely unlabeled, high-speed removal is immediately triggered; when If the label is determined to be damaged or misaligned, a secondary alarm is triggered and an image snapshot is recorded (if an auxiliary vision module is available) for process analysis.

[0013] This application also provides a transparent bottle / bag product rejection system based on label presence detection, including a diffuse reflection photoelectric switch, multiple fluorescent detection sensors arranged in a ring, a PLC controller, a rejection cylinder, an audible and visual alarm light, an air source and connecting air pipes, and power and signal cables. The PLC controller has an embedded label presence determination logic module, used to execute the steps of any of the rejection methods described above, and communicates with each hardware component in real time via hardwiring or an industrial bus to achieve millisecond-level response closed-loop control. Through fluorescence characteristic difference detection, ring multi-angle array, integrity index modeling, and closed-loop rejection control, it forms significant technical advantages in terms of sensitivity, accuracy, and adaptability of transparent bottle / bag product label presence detection. Attached Figure Description

[0014] Figure 1The schematic diagram of the transparent bottle and bag product rejection system based on label presence detection provided in the embodiment of the present invention shows the diffuse reflection photoelectric switch, the ring fluorescence detection sensor array, the rejection cylinder and the audible and visual alarm light arranged sequentially on the conveyor line, and indicates the connection relationship between the PLC controller and each component. Figure 2 This is a schematic diagram of the annular distribution of the fluorescence detection sensor array on the cross-section of the bottle in an embodiment of the present invention, showing N fluorescence detection sensors evenly arranged around the cylindrical bottle body, and the effective detection width of a single sensor. The geometric relationship between the bottle and the diameter D of the bottle. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0016] This invention provides a method and system for rejecting transparent bottle / bag products based on label presence detection. The specific embodiments of this invention will be described in detail below with reference to the accompanying drawings. Figure 1 As shown, the rejection system in this embodiment includes a diffuse reflection photoelectric switch 2 installed on the conveyor line 1, multiple fluorescent detection sensors 3 arranged in a ring, a PLC controller 4, a rejection cylinder 5, an audible and visual alarm light 6, an air source 7 and connecting air pipes 8, a power supply 9, and signal cables 10. The diffuse reflection photoelectric switch 2 is used to detect whether transparent bottle / bag products have entered the inspection station; the fluorescent detection sensors 3 are arranged in a ring along the vertical cross-section of the product conveying direction, surrounding the circumference of the bottle to be tested; the PLC controller 4 has an embedded tag presence determination logic module, which communicates with each hardware component in real time via hardwiring or an industrial bus (such as Modbus, Profinet, etc.) to achieve closed-loop control with millisecond-level response.

[0017] In actual operation, when the transparent bottle / bag product moves at a constant speed along conveyor line 1 to the detection area, the diffuse reflection photoelectric switch 2 is triggered first. This switch outputs a high-level signal to the PLC controller 4 as a detection start signal. The PLC controller 4 then opens a detection window of fixed width. Its duration is determined by the formula Confirmed, among which This is the maximum axial length of the product (e.g., 200 mm). The effective diameter (e.g., 10 mm) of the light spot emitted by the fluorescence detection sensor 3 in the axial direction of the product. The operating speed of conveyor line 1 is (e.g., 0.5 m / s). Therefore, we can obtain... = (0.2 + 0.01) / 0.5 = 0.42 s. Within this time window, the PLC controller 4 continuously collects the output signals of all fluorescence detection sensors 3 to avoid signal crosstalk caused by the close spacing between adjacent products.

[0018] like Figure 2 As shown, the number N of fluorescence detection sensors 3 is optimized according to the bottle's geometric parameters, satisfying the formula: Where D is the diameter of the cylindrical bottle body (e.g., 60 mm). Let N be the effective detection width (e.g., 20 mm) of a single fluorescence detection sensor 3 on the bottle surface. Substituting into the calculation, we get N ≥ ⌈(π×60) / 20⌉ = ⌈9.42⌉ = 10. Therefore, in this embodiment, a total of 10 fluorescence detection sensors 3 are arranged in a ring array, evenly distributed around the cross-section of the bottle, with an included angle of 36° between adjacent sensors. At the same time, by reasonably designing the optical structure, we ensure that the overlap rate of the detection areas of adjacent sensors is not less than 15%, thereby effectively eliminating the detection blind zone caused by the slight rotation of the bottle during transportation.

[0019] Each fluorescence detection sensor 3 includes an ultraviolet light source and a fluorescence receiving unit. The ultraviolet light source emits ultraviolet light with a wavelength of 365nm, which penetrates the transparent bottle material (such as PET, PE, or PVC) and the internal liquid (such as water, saline solution, or medicine). Since the bottle and its contents do not exhibit spontaneous fluorescence under this excitation wavelength, no interference signal is generated. However, if a paper label containing fluorescent material is affixed to the bottle (usually fluorescent whitening agents or special fluorescent dyes are added to the printing ink), it will excite visible fluorescence with a wavelength of approximately 450nm under 365nm ultraviolet light irradiation. The fluorescence receiving unit is equipped with a bandpass filter with a center wavelength of 450nm and a half-width ±20nm, allowing only fluorescence signals in the 430–470nm band to pass through, effectively suppressing interference from ambient stray light (such as sunlight, LED lighting, etc.) and significantly improving the signal-to-noise ratio. The receiving end converts the fluorescence intensity into an analog voltage signal, which is then input to the PLC controller 4 after analog-to-digital conversion.

[0020] PLC controller 4 in the detection window The output signal of each fluorescence detection sensor 3 Normalization is performed to obtain normalized fluorescence intensity values ​​(range 0–1). Then, based on a preset fluorescence response threshold τ (e.g., τ = 0.15), a binary response state is constructed using the step function σ(·). , the function determines the response of each sensor as "tag detected" (1) or "tag not detected" (0). The response states of all N sensors within a unit detection period are arranged in the order of spatial position, forming a 1×N binary tag presence matrix M = [m1, m2, ..., , where . This matrix is not only used for integrity assessment but also for subsequent fault location - for example, if multiple consecutive elements in the matrix are 0, it may indicate local detachment or displacement of the tag.

[0021] Based on this matrix, the PLC controller 4 further calculates the tag coverage integrity index , which is defined as: , this index represents the proportion of the product's circumference effectively covered by the tags. For example, if 7 out of 10 sensors detect the fluorescence signal, then = 7 / 10 = 0.7. The integrity threshold θ is dynamically set according to the production process requirements, and its value range is 0.3 ≤ θ ≤ 0.6. In this embodiment, θ = 0.5 is set, that is, it is required that the tag covers at least 50% of the bottle body circumference to be considered qualified. If ≥ θ, it is determined as a qualified product and no action is triggered; if = 0, indicating that there is no tag at all, the PLC controller 4 immediately generates a high-speed rejection instruction; if 0 < < θ, it is determined that the tag is damaged, warped or attached offset. At this time, in addition to generating a rejection instruction, an audible and visual alarm light 6 is also synchronously triggered to emit a secondary alarm (such as yellow flashing), and the event timestamp, value and the corresponding tag presence matrix M are recorded into the PLC log module for subsequent quality traceability and process analysis. If the system is equipped with an auxiliary vision module (such as an industrial camera), an image snapshot can also be triggered for saving at this time to facilitate manual review.

[0022] When the PLC controller 4 determines that an unqualified product needs to be rejected, it immediately outputs a high-level signal to the solenoid valve of the rejection cylinder 5. The rejection cylinder 5 is connected to the air source 7 through the connecting air pipe 8 and completes the extension action within 0.1 second after receiving the instruction. Its piston rod laterally intercepts the target product on the conveyor line 1 and pushes it into the waste collection channel (not shown in the figure) to achieve physical separation. After the rejection is completed, the cylinder automatically resets and waits for the next instruction. The response time of the entire rejection process is less than 200 ms, which is sufficient to meet the rhythm requirements of a high-speed production line (such as 200 bottles per minute).

[0023] In addition, the system has a self-calibration function. When starting up the equipment or changing product specifications, the operator can input parameters such as the new bottle diameter D and the minimum allowable area ratio of the label through the HMI interface. The PLC controller 4 automatically recalculates the required number of fluorescence detection sensors N and the detection window. And the integrity threshold θ, and update the internal decision logic. For example, when switching to a bottle type with a diameter D = 80 mm, If the diameter remains at 20 mm, then N ≥ ⌈(π×80) / 20⌉ = ⌈12.56⌉ = 13. The system will enable 13 sensor channels (if the hardware supports expansion) to ensure detection coverage.

[0024] This invention is particularly suitable for online inspection of the label integrity of transparent packaging containers (such as infusion bags, mineral water bottles, and shampoo bottles) in the pharmaceutical, food, and daily chemical industries. Taking an infusion bag production line of a pharmaceutical company as an example, the bottle / bag material is a multi-layer co-extruded film, the contents are colorless and transparent sodium chloride injection solution, and the label is a white medical paper label containing fluorescent whitening agent. Under 365nm ultraviolet excitation, the label emits bright blue light (peak at 450nm), while the bottle / bag and the drug solution show no fluorescent background. The system operates stably, with a false rejection rate of less than 0.1% and a false negative rate of zero, significantly outperforming traditional color- or contrast-based visual inspection solutions.

[0025] In summary, this invention cleverly utilizes the difference between the fluorescent properties of labels and the non-fluorescent properties of bottles and bags, combined with annular multi-angle fluorescence detection, time-synchronized sampling, integrity index modeling, and closed-loop rejection control, to achieve high-precision and high-reliability online detection and automatic rejection of labels on transparent bottles and bags. It solves the technical problem of accurately identifying missing labels in transparent media, and has outstanding practical value and broad industrial application prospects.

Claims

1. A method for rejecting transparent bottle / bag products based on label presence detection, characterized in that, Includes the following steps: A diffuse reflection photoelectric switch (2) and an array of multiple fluorescence detection sensors (3) are set on the conveyor line (1). When the transparent bottle bag product enters the detection station, the diffuse reflection photoelectric switch (2) triggers the detection start signal. Based on the characteristic that the bottle bag body and the internal liquid have no fluorescence response to ultraviolet light with a wavelength of 365 nm, and the paper label contains fluorescent substances that can be excited, the fluorescence detection sensors (3) arranged at multiple angles irradiate and receive the product circumference through penetrating irradiation, and obtain the fluorescence response signal sequence of each fluorescence detection sensor (3). The product label existence confidence matrix is ​​constructed according to the fluorescence response signal sequence. Combined with the bottle body geometric parameters and the spatial layout of the fluorescence detection sensors (3), the label coverage integrity index is calculated, and the existence of a valid label is determined according to the index. If it is determined that there is no label or the label is missing, a rejection instruction is generated and the sound and light alarm light (6) is triggered simultaneously. Based on the rejection instruction, the rejection cylinder (5) is driven to perform a physical interception action to separate the unqualified product from the conveyor line (1). At the same time, the abnormal event is recorded to the log module of the PLC controller (4) for quality traceability.

2. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 1, characterized in that, The array of fluorescence detection sensors (3) is arranged in a ring shape along the vertical cross-section of the product conveying direction, and its number N satisfies the formula: Where D is the diameter of the cylindrical bottle body. The effective detection width of a single fluorescence detection sensor on the bottle surface. This represents the floor function, ensuring that the overlap rate of the detection areas of adjacent sensors is not less than 15%.

3. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 1, characterized in that: The label coverage integrity index The calculation method is as follows: ;in, For the first A fluorescence detection sensor at time The output normalized fluorescence intensity signal, To preset the fluorescence response threshold, This is a step function that outputs 1 when the input is greater than 0, and 0 otherwise.

4. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 3, characterized in that, The response states of all fluorescence detection sensors (3) within a unit detection cycle are mapped to a binary tag existence matrix according to their spatial positions. The element in the k-th column of the matrix indicates whether the k-th fluorescence detection sensor (3) has detected the tag fluorescence signal.

5. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 1, characterized in that, The condition for generating the rejection instruction is: when the tag coverage integrity index... It is triggered when θ is an integrity threshold, with a value range of 0.3 ≤ θ ≤ 0.

6.

6. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 1, characterized in that, The fluorescence detection sensor (3) emits ultraviolet light with a wavelength of 365 nm, and the receiving end is equipped with a bandpass filter with a center wavelength of 450 nm and a half width at half maximum (WWHM) of ±20 nm.

7. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 1, characterized in that, The PLC controller (4) opens a fixed-width detection window after the diffuse reflection photoelectric switch (2) is triggered. Fluorescence signals are sampled only within this window. satisfy ,in This is the maximum axial length of the product. The diameter of the light spot of the fluorescence detection sensor (3) is... The speed of the conveyor line (1) is given.

8. The method for rejecting transparent bottle / bag products based on label presence detection as described in claim 5, characterized in that, The step of determining whether a valid label exists based on the label coverage integrity index further includes: when It was determined to be a qualified product at that time; When it is determined to be completely unlabeled; when The label is determined to be damaged or misaligned.

9. A transparent bottle / bag product rejection system based on label presence detection, characterized in that, It includes a diffuse reflection photoelectric switch (2), multiple fluorescent detection sensors (3) arranged in a ring, a PLC controller (4), a rejection cylinder (5), an audible and visual alarm light (6), an air source (7) and connecting air pipes (8), a power supply (9) and signal cables (10); the PLC controller (4) is embedded with a tag presence determination logic module, which is used to execute the rejection method as described in any one of claims 1 to 8, and communicates with each hardware component in real time through hard wiring or industrial bus.

10. The transparent bottle / bag product rejection system based on label presence detection as described in claim 9, characterized in that, The number of fluorescence detection sensors (3) and the detection window The integrity threshold θ can be automatically updated by the PLC controller (4) based on the input parameters of bottle diameter and minimum allowable area ratio of label.

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