Label intelligent positioning printing production method based on visual detection

Abstract

The present application relates to the technical field of label printing, and specifically discloses a label intelligent positioning and printing production method based on visual detection. The present application comprises: S1, driving the label roll to move along the conveying direction, and obtaining a first voltage sampling signal corresponding to the label gap position through a light emitter and a light receiver arranged on the conveying path; obtaining the voltage sampling signal of the label gap and the label region through the light emitter and the light receiver at the front end of the conveying, and adaptively determining the input voltage reference value through the "maximum difference" mode, and further determining the input pulse reference value, so that the beat signal is no longer dependent on the fixed threshold value, but is automatically calibrated according to the current material state. In this way, when the label transparency changes, the ink coverage is uneven, or the ambient light fluctuates, the label gap and the label region can still be stably distinguished, the reliability of the beat signal is ensured from the source, and the problem of easy false triggering or missed triggering in the traditional electric eye scheme is avoided.

Description

Technical Field

[0001] This invention relates to the field of label printing technology, and more specifically to a label intelligent positioning printing production method based on visual detection. Background Technology

[0002] In the label printing and subsequent processing, roll-to-roll labels typically require multiple steps such as printing, transfer, lamination, and die-cutting to be completed sequentially in a continuous conveying state. Due to the spatial intervals between each step, the labels are inevitably affected by tension fluctuations, material expansion and contraction, and equipment response delays during the conveying process, resulting in positional shifts between different workstations.

[0003] In existing technologies, photoelectric sensors are often used to detect label gaps or color marks, triggering cycle signals with a fixed threshold to control the timing of each workstation. However, this method relies on a pre-set detection threshold. When the light transmittance of the label material changes, the printing ink coverage is uneven, or the ambient light interference changes, the amplitude of the detection signal will fluctuate, easily leading to unstable gap recognition or even false triggering, which in turn affects the cycle consistency of the entire production line.

[0004] To improve positioning accuracy, some solutions incorporate visual inspection, achieving precise positioning by recognizing label patterns or edge positions. However, under actual high-speed transport conditions, visual images are easily affected by motion blur, reflections, or partial occlusion, leading to fluctuations or even failures in recognition results. Furthermore, visual inspection is typically used for single-station correction and is insufficient to compensate for front-end cycle time errors, potentially resulting in accumulated errors over long-term operation.

[0005] In addition, in existing systems, cycle control and position correction are usually completed independently by different modules, lacking a unified calibration and coordination mechanism, which makes it impossible for cycle error and spatial offset to form a closed-loop correction relationship.

[0006] Therefore, it is necessary to provide a new technical solution to overcome the above-mentioned defects. Summary of the Invention

[0007] The purpose of this invention is to provide a visual inspection-based intelligent positioning printing production method for labels that can effectively solve the above-mentioned technical problems.

[0008] To achieve the objectives of this invention, the following technical solution is adopted: A label intelligent positioning printing production method based on vision detection includes: S1, driving the label roll to move along the conveying direction, and acquiring a first voltage sampling signal corresponding to the label gap position and a second voltage sampling signal corresponding to the label area position through a light emitter and a light receiver set on the conveying path; S2. Determine the input voltage reference value based on the difference between the first voltage sampling signal and the second voltage sampling signal, and adjust the input pulse based on the input voltage reference value to obtain the input pulse reference value for marking the tag beat; S3. Perform initial position calibration on the tag based on the input pulse reference value; S4. Use a visual acquisition device to obtain label pattern, edge features or positioning mark information, and calculate the offset of the label relative to the target printing position; S5. Adjust the tension, speed or station phase during the label conveying process according to the offset to achieve precise alignment of the label at the printing station. S6. After alignment is completed, perform printing, transfer or die-cutting on the label.

[0009] Furthermore, the input voltage reference value is the input voltage corresponding to the maximum value of the difference between the first voltage sampling signal and the second voltage sampling signal under different input voltage conditions.

[0010] Furthermore, after determining the input voltage reference value, the input pulse is adjusted in steps and a third voltage sampling signal is acquired. When the third voltage sampling signal is within a preset range, the corresponding input pulse is used as the input pulse reference value.

[0011] Furthermore, the visual acquisition device is used to identify at least one of the pattern outline, edge line, or invisible positioning mark of the label.

[0012] Furthermore, the offset includes at least one of longitudinal offset, lateral offset, and rotational offset.

[0013] Furthermore, the adjustment includes changing the conveying tension or path angle of the label roll by driving the shaft roller with a servo motor.

[0014] Furthermore, when visual detection fails or image quality is below a preset threshold, the label is positioned and controlled solely based on the input pulse reference value.

[0015] Furthermore, during the tag transport process, the tag's moving speed information is obtained through a position detection device, and the offset is corrected based on the moving speed information.

[0016] Furthermore, after printing or transfer is completed, the label position is checked again by visual inspection, and the positioning parameters of subsequent labels are adjusted according to the check results.

[0017] Furthermore, the label is a composite structure label, including at least one of a printed layer, an adhesive layer, or an electronic tag layer.

[0018] Compared with existing technologies, this invention has the following advantages: By acquiring voltage sampling signals of the label gap and label area using a light emitter and light receiver at the front end of the conveying process, and adaptively determining the input voltage reference value through a "difference maximization" method, and further determining the input pulse reference value, the cycle signal no longer depends on a fixed threshold, but is automatically calibrated according to the current material state. This ensures stable differentiation between the label gap and label area even when label transparency changes, ink coverage is uneven, or ambient light fluctuates, guaranteeing the reliability of the cycle signal from the source and avoiding the problems of false triggering or missed triggering found in traditional photoelectric sensor solutions. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0020] Figure 1 This is a schematic diagram of the process of a visual inspection-based intelligent positioning printing production method for labels according to the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0022] In the description of this invention, it should be understood that the terms "center," "lateral," "longitudinal," "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. When a component is referred to as being "fixed to" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intermediate component. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0023] like Figure 1 As shown, this invention relates to a visual inspection-based intelligent positioning printing production method for labels, comprising: The label roll passes sequentially through the photoelectric detection area, the visual detection area, and the printing or die-cutting station along the predetermined conveying direction. Each module is arranged sequentially along the conveying path, so that the label completes the cycle establishment and position correction during the movement.

[0024] A light emitter and a light receiver are positioned at the front end of the conveying path, located on opposite sides of the label roll, ensuring the label is positioned between the light sources as it passes through. As the roll moves continuously, when the label gap area enters the light path, the light signal transmission is enhanced, and the light receiver outputs a corresponding first voltage sampling signal. When the label body area enters the light path, the light signal is partially blocked or reflected, resulting in the output of a second voltage sampling signal with a different amplitude. The control system stores the continuously acquired voltage signals and distinguishes between the gap area and the label area according to the time sequence.

[0025] During the initial operation of the system or during periodic calibration, the input voltage of the light emitter is adjusted stepwise by the control module with a preset step size. At each voltage value, a first voltage sampling signal and a second voltage sampling signal are collected, and the difference between the two is calculated. When the difference reaches its maximum, the corresponding input voltage is determined as the input voltage reference value. At this point, the signal distinction between the tag gap and the tag area is most obvious, thus enabling stable differentiation between the two states during subsequent detection and reducing the impact of material differences or environmental changes.

[0026] After determining the input voltage reference value, the control system further adjusts the input pulse in steps to ensure a stable time-domain output of the photoelectric detection signal. A corresponding third voltage sampling signal is acquired under each pulse condition. When the amplitude and fluctuation range of the third voltage sampling signal fall within a preset range, the pulse value is determined as the input pulse reference value. The preset range can be set based on historical sampling data, for example, using the mean of the signal's stable range ± a set range as the criterion. Through this method, the time-domain signal not only has clear amplitude distinctions but also stable repeatability in time.

[0027] Based on the input pulse reference value, the system performs initial position calibration on the label roll, that is, establishes a correspondence between the starting position of each label unit and the pulse beat, so that subsequent workstations can trigger actions according to this beat. This process establishes a unified beat benchmark for the entire production line, reducing the accumulation of errors caused by beat drift from the source.

[0028] A visual acquisition device is installed after the photoelectric detection area, facing the label surface and maintaining a fixed distance from the photoelectric detection area in the conveying direction. After acquiring the label image, the visual acquisition device first performs grayscale processing on the image and extracts the label outline or positioning feature points through edge extraction or threshold segmentation. Then, it performs geometric fitting on the extracted features to obtain the label's position parameters in the current image. These position parameters are then compared with a preset target position to calculate the label's offset. The offset may include longitudinal offset along the conveying direction, lateral offset perpendicular to the conveying direction, and rotational offset of the label.

[0029] Once the offset is calculated, the control system adjusts the conveying process accordingly. In this embodiment, a servo motor drives a roller positioned in the conveying path, causing the roller to oscillate within a small range, thereby changing the tension distribution of the roll material or the conveying path angle. When longitudinal offset exists, compensation is made by adjusting the conveying speed or cycle phase; when lateral or rotational offset exists, correction is achieved by changing the force state of the roll material on the roller. This multi-parameter linkage adjustment method can complete position correction before the label enters the printing station, thereby improving alignment accuracy and reducing scrap rate.

[0030] During actual operation, the vision acquisition device evaluates image quality in real time, for example, based on image sharpness, contrast, or feature recognition success rate. When the detected image quality falls below a preset threshold, the control system stops offset correction based on visual results and retains only the beat control mode based on the input pulse reference value. Since the front-end photoelectric detection has completed adaptive calibration, this beat signal has high stability, thus maintaining basic tag positioning control even in the event of visual failure, avoiding production interruption.

[0031] During continuous label conveying, the label's moving speed information can be obtained by setting a position detection device. This position detection device can be an encoder or a feedback unit connected to the drive motor, used to output the conveying speed in real time. When a speed change is detected, the control system dynamically corrects the offset based on the current speed, for example, by adjusting the cycle phase or compensation amount in advance, so that the label maintains its target position when it reaches the printing station, thereby reducing the impact of dynamic conditions on positioning accuracy.

[0032] After the label is printed or transferred, it continues to the downstream inspection area, where its actual position is acquired again through visual acquisition and compared with the target position. When a deviation is detected, it is fed back to the control system to adjust the input pulse parameters, tension parameters, or phase parameters of subsequent labels. Through this closed-loop correction method, the system continuously optimizes parameters during continuous production, thereby gradually improving the overall positioning accuracy and consistency.

[0033] In this embodiment, the label can be a composite label, which includes different functional layers such as a printing layer, an adhesive layer, or an electronic tag layer. Different structures have different effects on photoelectric signals and visual recognition. However, by combining photoelectric adaptive calibration with visual correction, the method can adapt to various label structures and improve its versatility.

[0034] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0035] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A label intelligent positioning printing production method based on visual detection, characterized in that, include: S1. Drive the label roll to move along the conveying direction, and obtain the first voltage sampling signal corresponding to the label gap position and the second voltage sampling signal corresponding to the label area position through the light emitter and light receiver set on the conveying path; S2. Determine the input voltage reference value based on the difference between the first voltage sampling signal and the second voltage sampling signal, and adjust the input pulse based on the input voltage reference value to obtain the input pulse reference value for marking the tag beat; S3. Perform initial position calibration on the tag based on the input pulse reference value; S4. Use a visual acquisition device to obtain label pattern, edge features or positioning mark information, and calculate the offset of the label relative to the target printing position; S5. Adjust the tension, speed or station phase during the label conveying process according to the offset to achieve precise alignment of the label at the printing station. S6. After alignment is completed, perform printing, transfer or die-cutting on the label.

2. The label intelligent positioning printing production method based on visual detection as described in claim 1, characterized in that, The input voltage reference value is the input voltage that corresponds to the maximum value of the difference between the first voltage sampling signal and the second voltage sampling signal under different input voltage conditions.

3. The label intelligent positioning printing production method based on visual detection as described in claim 2, characterized in that, After determining the input voltage reference value, the input pulse is adjusted in steps and a third voltage sampling signal is acquired. When the third voltage sampling signal is within a preset range, the corresponding input pulse is used as the input pulse reference value.

4. The label intelligent positioning printing production method based on visual detection as described in claim 3, characterized in that, The visual acquisition device is used to identify at least one of the following: the pattern outline, edge line, or invisible positioning mark of the label.

5. The label intelligent positioning printing production method based on vision detection as described in claim 4, characterized in that, The offset includes at least one of longitudinal offset, lateral offset, and rotational offset.

6. The label intelligent positioning printing production method based on vision detection as described in claim 5, characterized in that, The adjustment includes changing the conveying tension or path angle of the label roll by driving the rollers with a servo motor.

7. The label intelligent positioning printing production method based on vision detection as described in claim 6, characterized in that, When visual detection fails or image quality is below a preset threshold, the label is positioned and controlled solely based on the input pulse reference value.

8. The label intelligent positioning printing production method based on vision detection as described in claim 7, characterized in that, During the tag transport process, the moving speed information of the tag is obtained through a position detection device, and the offset is corrected based on the moving speed information.

9. The label intelligent positioning printing production method based on visual detection as described in claim 8, characterized in that, After printing or transfer is completed, the label position is checked again by visual inspection, and the positioning parameters of subsequent labels are adjusted according to the check results.

10. The label intelligent positioning printing production method based on vision detection as described in claim 9, characterized in that, The label is a composite label, including at least one of a printed layer, an adhesive layer, or an electronic tag layer.

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