Hybrid triggering method, control device and flaw detection system of line scanning camera
By adopting a hybrid trigger method in the online scanning camera system, the second time interval is calculated using multiple trigger signals and the width of the image strips, solving the problem of limitation in the prior art and realizing high-resolution image acquisition , reduces the limitation of the resolution of the encoder accuracy.
Patent Information
- Application Number
- CN202311029995.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-16
- Publication Date
- 2025-02-21
AI Technical Summary
The triggering methods of existing line scanning cameras have the problem of limited resolution, especially the encoder accuracy and meter wheel perimeter limit the minimum line width of the image bar, resulting in insufficient resolution.
Using a hybrid trigger method, the control device generates a plurality of first trigger signals and a plurality of second trigger signals according to the encoder output signal, calculates the second time interval using the width and detection distance of the image strip, and inserts the second trigger. The signal takes a picture bar with a control line scan camera.
Even with low-precision encoder, high-resolution object images can be generated, improving the resolution of defect detection systems without the need for high-precision and expensive encoders.
Smart Images
Figure CN119492744A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of automatic optical inspection (AOI), and in particular to a hybrid triggering method of a line scanning camera. Background Art
[0002] Generally speaking, semi-finished products or finished products manufactured using industrial technology must undergo quality inspection to determine whether they meet industrial standards, including cosmetic inspection and functional testing. Therefore, automated optical inspection (AOI) systems using machine vision technology have been developed and introduced into automated production lines to replace manpower to perform cosmetic inspections on industrial semi-finished products or finished products.
[0003] Figure 2 FIG. 1 is a stereogram of a conventional defect detection system. Figure 2 As shown, the defect detection system 1a is used to detect surface defects on a foil 3a transmitted by a roll-to-roll device 2a, and includes at least one line scanning camera 11a, a control device 12a, and an encoder 13a. During normal operation, the encoder 13a monitors the moving distance of the foil 3a and sends an encoder output signal to the control device 12a. It should be understood that by decoding the encoder output signal, the control device 12a can grasp the moving speed (i.e., moving distance) and moving direction of the foil 3a. Then, in accordance with the moving speed of the foil 3a, the control device 12a sends out multiple trigger signals in a time-sharing manner to control the line scanning camera 11a to perform line-by-line image acquisition on the foil 3a to obtain the following image: Figure 2 Image of foil shown.
[0004] It is worth mentioning that in order to ensure the accuracy of defect detection, it is necessary to set the resolution so that one defect has at least 3 pixels in the image. In other words, for a 90μm defect, the resolution must be set at 30μm / pixel. On the other hand, in image processing, vertical lines are usually used and horizontal columns are used. Figure 2 The foil image shown is composed of Y image strips, and each image strip has a line width.
[0005] As can be seen from the above description, the smaller the line width, the higher the resolution of the foil image. Practical experience shows that the line width is positively correlated with a time interval between the two trigger signals. In more detail, the time interval refers to the time interval between the i-th trigger signal and the i+1-th trigger signal sent to the line scan camera 11a, i=0~Y-1, and i and Y are both positive integers. For example, after receiving the i-th trigger signal, the line scan camera 11a is triggered to capture an i-th image strip from the foil 3a. In other words, the accuracy of the encoder 13a is positively correlated with the shortest moving distance of the foil 3a that it can monitor, that is, it is positively correlated with the time interval between the two trigger signals, and the line width is positively correlated with the time interval between the two trigger signals. Therefore, the relationship between resolution and encoder accuracy can be expressed by the following formula (i):
[0006]
[0007] In the above formula (i), C is the circumference of the encoder wheel 13a, and P is the accuracy of the encoder 13a, which is expressed as the number of pulses generated by the encoder 13a during one rotation of the wheel (i.e., the number of pulses contained in one frame of the encoder output signal).
[0008] From equation (1) and equation (2), it can be seen that the smaller the circumference of the millimeter wheel, the higher the resolution of the defect detection system 1a (e.g., 50μm / pixel→30μm / pixel). However, practical experience shows that the encoder 13a with a millimeter wheel is not easy to be installed on the roll-to-roll device 2a due to its small size. On the other hand, from equation (1) and equation (2), it can also be seen that the resolution of the defect detection system 1a can be improved by increasing the accuracy of the encoder 13a. However, in practice, a high-precision encoder 13a is inevitably accompanied by an expensive price.
[0009] In summary, the conventional triggering method of the line scan camera has the problem of limited resolution. In view of this, the inventor of this case has made great efforts to study and invent, and finally developed a hybrid triggering method of the line scan camera of the present invention. Summary of the invention
[0010] The main purpose of the present invention is to provide a hybrid triggering method, which is executed by a control device, so as to generate multiple first triggering signals and multiple second triggering signals according to a detection distance of an encoder to control a line scan camera to obtain multiple image strips from an object to form an object image, wherein the multiple second triggering signals are inserted between any two of the first triggering signals. In this way, when the hybrid triggering method of the present invention is applied, even if a low-precision encoder is used, the line scan camera can be triggered to generate a high-resolution object image.
[0011] To achieve the above object, the present invention provides an embodiment of the hybrid triggering method, which is executed by a control device, wherein the control device is integrated into a defect detection system including at least one line scan camera and an encoder, and the line scan camera is controlled by the control device to capture a plurality of image strips from an object to form an object image; the hybrid triggering method includes the following steps:
[0012] receiving an encoder output signal from the encoder, and generating a plurality of first trigger signals for time-sharing triggering the line scan camera according to the encoder output signal; wherein there is a first time interval between any two of the first trigger signals;
[0013] Calculating a second time interval according to the width of the image bar, the first time interval, and a detection distance of the encoder; and
[0014] Generate a plurality of second trigger signals for time-sharing triggering the line scan camera, wherein the plurality of second trigger signals are inserted between any two of the first trigger signals, the two second trigger signals have the second time interval, and there is a third time interval between the second trigger signal and the first trigger signal.
[0015] In one embodiment, the control device calculates the second time interval using the following formula (1) and formula (2):
[0016]
[0017]
[0018] Wherein, D is the detection distance, t IN1 is the first time interval, t IN2 is the second time interval, V is the rate, and R is the width of the image bar.
[0019] In one embodiment, the object is a foil-like object conveyed by a roll-to-roll device, and the foil-like object is any one selected from the group consisting of metal foil, a flexible substrate, paper, and a flexible substrate covered with an outer layer.
[0020] In one embodiment, the control device is any one selected from the group consisting of a circuit board assembly, an electronic device, a notebook computer, a desktop computer, an industrial computer, a tablet computer, and a smart phone.
[0021] The present invention also provides an embodiment of a control device for integration into a defect detection system including at least one line scan camera and an encoder; the control device is configured to execute a hybrid trigger method to generate a plurality of first trigger signals and a plurality of second trigger signals for controlling the line scan camera to capture a plurality of image strips from an object to form an object image, and the hybrid trigger method comprises the following steps:
[0022] receiving an encoder output signal from the encoder, and generating a plurality of first trigger signals for time-sharing triggering the line scan camera according to the encoder output signal; wherein there is a first time interval between any two of the first trigger signals;
[0023] Calculating a second time interval according to the width of the image bar, the first time interval, and a detection distance of the encoder; and
[0024] Generate a plurality of the second trigger signals for time-sharing triggering the line scan camera, wherein the plurality of the second trigger signals are inserted between any two of the first trigger signals, the two second trigger signals have the second time interval, and there is a third time interval between the second trigger signal and the first trigger signal.
[0025] In one embodiment, the control device is any one selected from the group consisting of a circuit board assembly, an electronic device, a notebook computer, a desktop computer, an industrial computer, a tablet computer, and a smart phone.
[0026] In one embodiment, the control device includes a processor and a memory, wherein the memory stores an application program including a plurality of subroutines, and the plurality of subroutines include:
[0027] a first subroutine, wherein the processor accesses the memory to execute the first subroutine, thereby decoding the encoder output signal to obtain the detection distance; and
[0028] A second subroutine, wherein the processor executes the second subroutine by accessing the memory, thereby executing the hybrid triggering method.
[0029] In one embodiment, the processor calculates the second time interval using the following formula (1) and formula (2):
[0030]
[0031]
[0032] Wherein, D is the detection distance, t IN1 is the first time interval, t IN2 is the second time interval, V is the rate, and R is the width of the image bar.
[0033] In one embodiment, the object is a foil-like object conveyed by a roll-to-roll device, and the foil-like object is any one selected from the group consisting of metal foil, a flexible substrate, paper, and a flexible substrate covered with an outer layer.
[0034] Furthermore, the present invention also provides an embodiment of a defect detection system, which is used to perform surface defect detection on a foil-like object transmitted by a roll-to-roll device, characterized in that the defect detection system includes at least one line scanning camera, an encoder and the control device of the present invention as described above. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 A three-dimensional diagram of a conventional defect detection system;
[0036] Figure 2 For drive Figure 1 An image of a foil-like object captured by a line scanning camera shown;
[0037] Figure 3 is a three-dimensional diagram of a defect detection system of the present invention;
[0038] Figure 4 is a block diagram of a defect detection system of the present invention;
[0039] Figure 5 For drive Figure 3 An image of a foil-like object captured by a line scanning camera shown;
[0040] Figure 6 A flow chart of a hybrid triggering method of the present invention;
[0041] Fig. 7A a plurality of first trigger signals and a first schematic timing diagram of the plurality of first trigger signals; and
[0042] Figure 7B is a schematic timing diagram of multiple first trigger signals and multiple first trigger signals.
[0043]
Explanation of symbols
[0044] 1a: Defect Detection System
[0045] 11a: Line scan camera
[0046] 12a: Control device
[0047] 13a: Encoder
[0048] 2a: Roll-to-roll equipment
[0049] 3a: Foil
[0050] 1: Defect detection system
[0051] 11: Line scan camera
[0052] 12: Control device
[0053] 12P: Processor
[0054] 12M: Memory
[0055] 12M1:Decoding unit
[0056] 12M2: Hybrid Trigger Unit
[0057] 13: Encoder
[0058] 2: Roll-to-roll equipment
[0059] 3: Foil
[0060] S1~S3: Steps
[0061] TS1: First trigger signal
[0062] TS2: Second trigger signal DETAILED DESCRIPTION
[0063] In order to more clearly describe the hybrid triggering method, control device, and defect detection system of a line scan camera of the present invention, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0064] Figure 3 is a three-dimensional diagram of a defect detection system of the present invention, and Figure 4 FIG. 1 is a block diagram of a defect detection system of the present invention. Figure 3 and Figure 4As shown, the defect detection system 1 is used to detect surface defects of a foil 3 transmitted by a roll-to-roll device 2, and includes at least one line scan camera 11, an encoder 12, and a control device 12. In a feasible embodiment, the foil 3 can be but not limited to metal foil, a flexible substrate, paper, or a flexible substrate covered with an outer layer. And the control device 12 can be but not limited to a circuit board assembly, an electronic device, a notebook computer, a desktop computer, an industrial computer, a tablet computer, or a smart phone.
[0065] Specifically, the control device 12 includes a processor 12P and a memory 12M, and the memory 12M stores an application program including a plurality of subroutines. Figure 4 As shown, the multiple subroutines include: a first subroutine presented by a decoding unit 12M1 and a second subroutine presented by a hybrid trigger unit 12M2. During normal operation, the encoder 13 monitors the moving distance of the foil 3 transmitted by the roll-to-roll device 2 and sends an encoder output signal to the processor 12P. Afterwards, the processor 12P accesses the memory 12M to execute the first subroutine (i.e., the decoding unit 12M1), thereby decoding the encoder output signal to obtain a detection distance (i.e., the moving distance of the foil 3). Next, in conjunction with the moving speed (i.e., the moving distance) of the foil 3 and the accuracy of the encoder 13, the control device 12 accesses the memory 12M to execute the second subroutine, thereby executing a hybrid trigger method of the present invention, thereby generating multiple first trigger signals and multiple second trigger signals for controlling the line scan camera 11 to capture multiple image strips from the foil 3 to form an object image (such as Figure 5 shown).
[0066] Figure 6 FIG. 1 is a flow chart of a hybrid triggering method of the present invention. Figure 6 As shown, the method flow first executes step S1: receiving an encoder output signal from the encoder 13, and generating a plurality of the first trigger signals for time-sharing triggering the line scan camera 11 according to the encoder output signal. Fig. 7A is a first schematic timing diagram of a plurality of first trigger signals and a plurality of first trigger signals. Fig. 7A As shown, after decoding the encoder output signal, the processor 12P obtains a detection distance (i.e., moving distance) of the foil 3. Then, according to the accuracy of the encoder 13a and the detection distance, the processor 12P can generate a plurality of first trigger signals TS1, and any two of the first trigger signals TS1 have a first time interval t IN1 .
[0067] It should be understood that the first time interval t IN1 Refers to the time interval between the i-th first trigger signal TS1 and the i+1-th first trigger signal TS1 sent to the line scan camera 11a, i=0~Y-1 (i.e., Figure 5 For example, after receiving the i-th first trigger signal TS1, the line scan camera 11 is triggered to capture an i-th image strip from the foil 3. Therefore, the accuracy of the encoder 13 is positively correlated with the shortest moving distance of the foil 3 that it can monitor (i.e., the shortest detection distance), that is, positively correlated with the time interval between the two first trigger signals TS1 (i.e., the time interval between the two trigger signals), and the line width is positively correlated with the first time interval between the two trigger signals. Therefore, the minimum value of the line width is limited by the accuracy of the encoder and / or the circumference of its meter wheel.
[0068] Continue, as Figure 6 As shown, the method flow then executes step S2: a second time interval is calculated according to the width of the image strip, the first time interval and a detection distance of the encoder 13. Then, the method flow executes step S3: a plurality of second trigger signals are generated for time-sharing triggering the line scan camera 11. Specifically, the processor 12P calculates the second time interval t using the following equations (1) and (2): IN2 :
[0069]
[0070]
[0071] In the above formulas (1) and (2), D is the detection distance, t IN1 is the first time interval, t IN2 is the second time interval, V is the rate, and R is the width of the image strip. As shown in FIG7 , the second time interval t is calculated. IN2 Afterwards, the processor 12P can then generate a plurality of second trigger signals TS2 for time-sharing triggering the line scan camera 11, wherein the plurality of second trigger signals TS2 are inserted between any two of the first trigger signals TS1, and the two second trigger signals TS2 have the second time interval t IN2 , and there is a third time interval t between the second trigger signal TS2 and the first trigger signal TS1 IN3 Thus, the processor 12P sends a plurality of first trigger signals and a plurality of second trigger signals to the line scan camera 11, thereby controlling the line scan camera 11 to capture Y image strips from the foil 3 to form the following image strips: Figure 5The foil image shown. And, from the above formula (2), it can be known that the line width of each image strip is R = t IN2 In other words, the resolution of the foil image is no longer directly related to the accuracy of the encoder 13 and / or the circumference of the meter wheel.
[0072] Figure 7B is a schematic timing diagram of a plurality of first trigger signals and a second schematic timing diagram of a plurality of first trigger signals. Fig. 7A and Figure 7B It can be known that in Figure 7B The first time interval t IN1 This can be understood as the original encoder 13 being replaced by another one with lower precision. IN1 and D are known, therefore, when the target line width (ie, R value) of the image strip is determined, the processor 12P calculates the second time interval t using the above formulas (1) and (2): IN2 , and then generates a plurality of second trigger signals TS2 for triggering the line scan camera 11 in a time-sharing manner.
[0073] In summary, even if the defect detection system 1 uses a low-longitude encoder 13 and the minimum line width of the image strip is limited, the control device 12 can also generate a plurality of second trigger signals TS2 inserted between two second trigger signals TS1 in the case of applying the hybrid trigger method of the present invention, thereby further shortening the line width of the image strip, thereby improving the resolution of the foil image including Y image strips. In other words, in the case of applying the hybrid trigger method of the present invention, the defect detection system 1 is allowed to be used with a low-precision, cheap encoder, without the need for a high-precision, expensive encoder.
[0074] Thus, the above is a complete and clear description of the hybrid triggering method, control device, and defect detection system of a line scan camera proposed by the present invention. It must be emphasized that the above detailed description is a specific description of a feasible embodiment of the present invention, but the embodiment is not used to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the technical spirit of the invention should be included in the patent scope of this case.
Claims
1. A hybrid triggering method, characterized in that: The method is executed by a control device, wherein the control device is integrated into a defect detection system including at least one line scan camera and an encoder, and the line scan camera is controlled by the control device to capture a plurality of image strips from an object to form an object image; the hybrid triggering method comprises the following steps: receiving an encoder output signal from the encoder, and generating a plurality of first trigger signals for time-sharing triggering the line scan camera according to the encoder output signal; wherein there is a first time interval between any two of the first trigger signals; Calculating a second time interval according to the width of the image bar, the first time interval, and a detection distance of the encoder; and Generate a plurality of second trigger signals for time-sharing triggering the line scan camera, wherein the plurality of second trigger signals are inserted between any two of the first trigger signals, the two second trigger signals have the second time interval, and there is a third time interval between the second trigger signal and the first trigger signal.
2. The hybrid triggering method according to claim 1, characterized in that: The control device calculates the second time interval using the following formula (1) and formula (2): Wherein, D is the detection distance, t IN1 is the first time interval, t IN2 is the second time interval, V is the rate, and R is the width of the image bar.
3. The hybrid triggering method according to claim 1, characterized in that: The object is a foil-like object conveyed by a roll-to-roll device, and the foil-like object is any one selected from the group consisting of metal foil, a flexible substrate, paper, and a flexible substrate covered with an outer layer.
4. The hybrid triggering method according to claim 1, characterized in that: The control device is any one selected from the group consisting of a circuit board assembly, an electronic device, a notebook computer, a desktop computer, an industrial computer, a tablet computer, and a smart phone.
5. A control device for integration into a defect detection system comprising at least one line scan camera and an encoder; characterized in that: The control device is configured to execute a hybrid triggering method to generate a plurality of first triggering signals and a plurality of second triggering signals for controlling the line scan camera to capture a plurality of image strips from an object to form an object image, and the hybrid triggering method comprises the following steps: receiving an encoder output signal from the encoder, and generating a plurality of first trigger signals for time-sharing triggering the line scan camera according to the encoder output signal; wherein there is a first time interval between any two of the first trigger signals; Calculating a second time interval according to the width of the image bar, the first time interval, and a detection distance of the encoder; and Generate a plurality of the second trigger signals for time-sharing triggering the line scan camera, wherein the plurality of the second trigger signals are inserted between any two of the first trigger signals, the two second trigger signals have the second time interval, and there is a third time interval between the second trigger signal and the first trigger signal.
6. The control device according to claim 5, characterized in that The control device is any one selected from the group consisting of a circuit board assembly, an electronic device, a notebook computer, a desktop computer, an industrial computer, a tablet computer, and a smart phone.
7. The control device according to claim 5, characterized in that The control device includes a processor and a memory, wherein the memory stores an application program including a plurality of subroutines, and the plurality of subroutines include: a first subroutine, wherein the processor accesses the memory to execute the first subroutine, thereby decoding the encoder output signal to obtain the detection distance; and A second subroutine, wherein the processor executes the second subroutine by accessing the memory, thereby executing the hybrid triggering method.
8. The control device according to claim 7, characterized in that The processor calculates the second time interval using the following formula (1) and formula (2): Wherein, D is the detection distance, t IN1 is the first time interval, t IN2 is the second time interval, V is the rate, and R is the width of the image bar.
9. The control device according to claim 5, characterized in that: The object is a foil-like object conveyed by a roll-to-roll device, and the foil-like object is any one selected from the group consisting of metal foil, a flexible substrate, paper, and a flexible substrate covered with an outer layer.
10. A defect detection system for detecting surface defects of a foil conveyed by a roll-to-roll device, characterized in that: The defect detection system comprises at least one line scan camera, an encoder and a control device as claimed in any one of claims 5 to 9.