Optical measurement device for glue height detection in narrow space and detection method

Abstract

The invention discloses an optical measurement device and detection method for glue height detection in a narrow space, and the device comprises an imaging assembly which comprises a CCD camera and a lens thereof; the optical steering assembly is arranged in front of a light path of the lens; the mechanical adjusting assembly is connected with the optical steering assembly; the data processing and control assembly is in communication connection with the imaging assembly and the mechanical adjusting assembly; controlling a mechanical adjusting assembly to drive the rectangular prism to move to a detection position; controlling an imaging assembly, and capturing a sequence image through a rectangular prism; performing three-dimensional scanning reconstruction processing on the sequence image, and extracting a height value of the highest point of the glue surface in the region relative to a predetermined reference surface; and performing qualification judgment based on the height value. Light path turning is achieved through a right-angle prism capable of being accurately positioned, an image of a side face glue dispensing area in a narrow space is obtained, the height of the highest point of glue is extracted in combination with a three-dimensional scanning reconstruction algorithm, and therefore direct and non-contact quantitative detection of the height of the glue in the hidden space is achieved.

Description

Technical Field

[0001] This invention belongs to the field of optical precision measurement technology, and relates to an optical measurement device and detection method for detecting the height of glue in a confined space. Background Technology

[0002] In the assembly of precision components such as microelectronic components and voice coil motors (VCMs), adhesives are often used to fix components such as magnets and coils. The quality of adhesive application, especially the precise control of its height (or amount), directly determines the mechanical strength and reliability of the bond. Insufficient adhesive height will result in a reduced effective bonding area and insufficient bond strength, making components prone to detachment during subsequent use or environmental testing. Conversely, excessive adhesive height will cause adhesive overflow, contaminating adjacent functional components, leading to decreased product performance or even short-circuit failure.

[0003] Currently, CCD-based vision inspection equipment is widely used on production lines for automated inspection of the dispensing process. However, existing mainstream CCD inspection technologies have inherent limitations: see [link to relevant documentation]. Figure 4 It is usually based on the top-down two-dimensional planar imaging principle, and determines the presence of glue and the accuracy of its planar coverage by analyzing the contrast, color or contour shape of the image. It cannot obtain information about the glue in the third dimension, that is, the height direction perpendicular to the workpiece surface.

[0004] Therefore, existing technologies can essentially only perform "presence / absence detection" and "two-dimensional positioning detection," but cannot quantitatively measure and determine the critical process parameter of adhesive height. This makes the following two types of latent defects highly susceptible to flowing into subsequent processes:

[0005] Insufficient Adhesive Defect: From a top-down two-dimensional perspective, the adhesive outline may perfectly meet the requirements, but its actual height is lower than the process standard, posing a potential risk of insufficient bond strength. Adhesive Overflow Defect: Excessive accumulation of adhesive in the height direction, although not clearly exceeding the planar outline, already poses a risk of overflow or has actually caused microscopic contamination to adjacent structures.

[0006] In summary, existing two-dimensional vision inspection methods can no longer meet the growing quality demands for precise three-dimensional shape control of adhesive application. The industry urgently needs a new technological solution that can accurately measure adhesive height online, quickly, and non-contactly, and automatically determine quality accordingly, in order to fundamentally eliminate product reliability issues caused by improper adhesive height. Summary of the Invention

[0007] The purpose of this invention is to address the problem that existing two-dimensional vision inspection methods can no longer meet the growing quality requirements for precise three-dimensional shape control of adhesive application, and to provide an optical measurement device and inspection method for detecting the height of adhesive in confined spaces.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] An optical measuring device for detecting the height of glue in a confined space, comprising:

[0010] Imaging components, including a CCD camera and its lens;

[0011] An optical steering assembly is disposed in front of the optical path of the lens. The assembly includes at least one right-angle prism, which is configured such that its incident right-angle surface receives an imaging beam from the glue area of ​​the workpiece being measured, and the beam undergoes total internal reflection on its inclined surface and exits from its exit right-angle surface, thereby achieving a 90° optical path deflection of the imaging beam.

[0012] A mechanical adjustment assembly, connected to the optical steering assembly, is used to adjust at least the position and lateral yaw angle of the right-angle prism within the confined space;

[0013] A data processing and control component is communicatively connected to the imaging component and the mechanical adjustment component;

[0014] The data processing and control component is configured to perform the following operations:

[0015] Control the mechanical adjustment assembly to drive the right-angle prism to a preset detection position;

[0016] The imaging component is controlled to capture a sequence of images containing the side view contour of the glue area through the right-angle prism;

[0017] The sequence of images is subjected to three-dimensional scanning and reconstruction processing to determine the fixed test area of ​​the glue area, and the height value of the highest point of the glue surface in the area relative to the predetermined reference plane is extracted.

[0018] The qualification is determined based on the height value.

[0019] The optical steering component is a single right-angle prism, the overall size of which is designed to extend into the inner cavity of the coil winding of the VCM voice coil motor stator assembly, and the incident right-angle surface is directly opposite the glue area dotted on the inner wall of the stator.

[0020] The device is used to detect the adhesive dispensing height on the side wall of the VCM stator. The predetermined reference surface is the uncoated plane of the inner wall of the stator. The data processing and control component automatically fits the reference surface by analyzing image or point cloud data.

[0021] The mechanical adjustment component includes a multi-dimensional precision motion platform, on which the right-angle prism is fixed by a mirror mount. The data processing and control component drives the multi-dimensional precision motion platform to achieve precise adjustment of the position of the right-angle prism in the X, Y, and Z directions and the angle around at least one rotation axis.

[0022] It also includes an active illumination component, which is arranged to project structured light or illumination light of a specific wavelength onto the adhesive area of ​​the workpiece under test, and the optical steering component together with the imaging component constitutes part of the light path that receives the illumination light after it is modulated by the adhesive surface and reflected.

[0023] In the data processing and control component, the operation of performing three-dimensional scanning and reconstruction processing on the sequence images, determining the fixed test area, and extracting the height value of the highest point specifically includes:

[0024] Based on the sequence of images, the three-dimensional point cloud data of the glue area is reconstructed using triangulation or focused depth sounding.

[0025] In the three-dimensional point cloud data, a rectangular or circular area corresponding to the theoretical center of glue application is defined as the fixed test area based on the preset workpiece coordinates.

[0026] Calculate the Z coordinates of all points within the fixed test area, and identify the maximum value of the Z coordinates as the height of the highest point on the adhesive surface.

[0027] The optical design of the right-angle prism satisfies the following condition: at the target working distance, both its incident right-angle surface and its exit right-angle surface are located within the depth of field of the CCD camera lens, to ensure the capture of images with clear outlines.

[0028] It also includes a calibration component comprising a standard step block with a known height; the data processing and control component is configured to periodically control the device to image and measure the standard step block, and to compensate the height measurement algorithm for parameters based on the deviation between the measurement results and the known height.

[0029] The data processing and control component is further configured to: extract the width or volume information of the glue area while extracting the height value of the highest point, and combine the height value to perform a multi-dimensional comprehensive quality judgment.

[0030] An online glue height detection method based on optical steering, applied to the device as described in any of the preceding items, includes the following steps:

[0031] S1, the optical probe with an integrated right-angle prism is positioned at the entrance of the space to be measured by a mechanical adjustment component;

[0032] S2, control the mechanical adjustment component to place the right-angle prism inside the space and adjust its orientation so that the CCD camera can clearly image the area of ​​the adhesive to be tested through the prism;

[0033] S3, drive the right-angle prism or the imaging component to perform scanning motion, while the CCD camera acquires a series of glue outline images obtained from different perspectives through the prism's rotation;

[0034] S4, The series of images are reconstructed in three dimensions using an image processing algorithm, and a preset fixed test area is located in the reconstructed three-dimensional model;

[0035] S5. Calculate the height of the highest point on the adhesive surface within the fixed test area, compare it with a preset qualified threshold, and output the test result to control product sorting.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The optical measurement device for detecting adhesive height in confined spaces in this invention achieves a 90° optical path rotation through a miniaturized right-angle prism that can be precisely positioned. This allows a CCD camera to directly acquire a clear side-view contour image of the adhesive application area within the confined space. Combined with a 3D scanning reconstruction algorithm, the height of the highest point of the adhesive is accurately extracted, thus achieving, for the first time, direct, non-contact quantitative detection of adhesive height in such hidden spaces. This solution not only overcomes the technical bottleneck of traditional 2D vision's inability to measure side adhesive height but also significantly improves the objectivity and consistency of the detection through a fully automated positioning, imaging, and judgment process. It can reliably identify hidden defects such as insufficient adhesive or potential overflow, fundamentally eliminating bonding failures or product performance problems caused by improper adhesive height. This has outstanding value in improving the yield and reliability of precision electronic assembly. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the optical measuring device for detecting glue height in a confined space according to the present invention.

[0040] Figure 2 This is a schematic diagram of the optical measurement device of the present invention.

[0041] Figure 3This is a schematic diagram of the principle of total internal reflection using a prism in this invention;

[0042] Figure 4 This is a schematic diagram of a testing device in the existing technology. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0045] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0046] The present invention will now be described in further detail with reference to the accompanying drawings:

[0047] See Figure 1 This is a schematic diagram of the optical measurement device for detecting glue height in a confined space according to the present invention; it includes:

[0048] Imaging components, including a CCD camera and its lens;

[0049] An optical steering assembly, positioned in front of the lens's optical path, comprises at least one right-angle prism. This prism is configured such that its incident right-angle face receives an imaging beam from the adhesive area of ​​the workpiece being measured. The beam undergoes total internal reflection on its inclined surface and exits from its exit right-angle face, thus achieving a 90° optical path deflection of the imaging beam. The optical steering assembly is a single right-angle prism, its overall dimensions designed to extend into the coil winding cavity of the VCM voice coil motor stator assembly, with the incident right-angle face directly facing the adhesive area dotted on the stator's inner wall. The device is used to detect the adhesive dotting height on the VCM stator sidewall. The predetermined reference plane is the un-adhesive plane of the stator's inner wall, and the data processing and control assembly automatically fits this reference plane by analyzing image or point cloud data. The optical design of the right-angle prism satisfies the following: at the target working distance, both its incident and exit right-angle faces are within the depth of field of the CCD camera lens to ensure the capture of a sharp image.

[0050] A mechanical adjustment component, connected to the optical steering component, is used to adjust at least the position and lateral yaw angle of the right-angle prism within the confined space. The mechanical adjustment component includes a multi-dimensional precision motion platform, on which the right-angle prism is fixed by a mirror mount. The data processing and control component drives the multi-dimensional precision motion platform to achieve precise adjustment of the position of the right-angle prism in the X, Y, and Z directions and the angle around at least one rotation axis.

[0051] A data processing and control component is communicatively connected to the imaging component and the mechanical adjustment component;

[0052] The data processing and control component is configured to perform the following operations:

[0053] Control the mechanical adjustment assembly to drive the right-angle prism to a preset detection position;

[0054] The imaging component is controlled to capture a sequence of images containing the side view contour of the glue area through the right-angle prism;

[0055] Performing 3D scanning and reconstruction processing on the sequence of images to determine a fixed test area for the adhesive region, and extracting the height value of the highest point on the adhesive surface within this area relative to a predetermined reference plane; the specific operations of performing 3D scanning and reconstruction processing on the sequence of images to determine the fixed test area and extracting the height value of the highest point include:

[0056] Based on the sequence of images, the three-dimensional point cloud data of the glue area is reconstructed using triangulation or focused depth sounding.

[0057] In the three-dimensional point cloud data, a rectangular or circular area corresponding to the theoretical center of glue application is defined as the fixed test area based on the preset workpiece coordinates.

[0058] Calculate the Z coordinates of all points within the fixed test area, and identify the maximum value of the Z coordinates as the height of the highest point on the adhesive surface.

[0059] While extracting the height value of the highest point, the width or volume information of the glue area is also extracted, and a multi-dimensional comprehensive quality judgment is made in combination with the height value.

[0060] The qualification is determined based on the height value.

[0061] An active illumination assembly is arranged to project structured light or illumination light of a specific wavelength onto the adhesive area of ​​the workpiece under test, and the optical steering assembly and the imaging assembly together constitute part of the light path that receives the illumination light after it is modulated by the adhesive surface and reflected.

[0062] A calibration component comprising a standard step block with a known height; the data processing and control component is configured to periodically control the device to image and measure the standard step block, and to compensate the height measurement algorithm for parameters based on the deviation between the measurement results and the known height.

[0063] An online glue height detection method based on optical steering, as described in this invention, includes the following steps:

[0064] S1, the optical probe with an integrated right-angle prism is positioned at the entrance of the space to be measured by a mechanical adjustment component;

[0065] S2, control the mechanical adjustment component to place the right-angle prism inside the space and adjust its orientation so that the CCD camera can clearly image the area of ​​the adhesive to be tested through the prism;

[0066] S3, drive the right-angle prism or the imaging component to perform scanning motion, while the CCD camera acquires a series of glue outline images obtained from different perspectives through the prism's rotation;

[0067] S4, The series of images are reconstructed in three dimensions using an image processing algorithm, and a preset fixed test area is located in the reconstructed three-dimensional model;

[0068] S5. Calculate the height of the highest point on the adhesive surface within the fixed test area, compare it with a preset qualified threshold, and output the test result to control product sorting.

[0069] like Figure 3 The diagram illustrates the principle of total internal reflection using a prism in this invention. The optical path works as follows: The imaging beam originates from the surface of the adhesive being tested and is incident perpendicularly on the first right-angled facet (incident facet) of the prism. Due to the absence of refraction during perpendicular incidence, the beam propagates in a straight line to the inclined facet. According to Snell's law, when the beam travels at a 45° angle from glass (optically denser medium, n≈1.5) to air (optically less dense medium, n=1.0), its angle of incidence is much greater than the critical angle (≈42°), thus resulting in total internal reflection. After the reflected beam deflects 90°, it is incident perpendicularly on the second right-angled facet (exit facet) and exits again without refraction, entering the camera lens. This process achieves a perfect 90° reversal of the line-of-sight direction with virtually no aberrations introduced.

[0070] Example

[0071] This embodiment describes an optical measuring device and its working method for detecting the height of adhesive applied to the inner wall of a voice coil motor (VCM) stator. The optical measuring device mainly includes the following components:

[0072] The imaging component uses a 5-megapixel global shutter CCD industrial camera, equipped with a telecentric lens with a focal length of 35mm, to ensure a constant image magnification at different working distances and reduce measurement errors.

[0073] The optical steering assembly is centered around a custom-designed, miniaturized right-angle prism. This prism is made of K9 optical glass, with a right-angle side length of 2.5mm, and its bevels are finely polished and coated with an enhanced total reflection film. The prism is secured by an aluminum alloy mount. Its design allows the entire assembly to have a cross-sectional dimension of less than Φ3mm, enabling it to easily fit into the coil cavity of a typical VCM stator (typically Φ3.5-Φ4.5mm in diameter).

[0074] The mechanical adjustment assembly is a four-axis precision motion platform, including three linear axes (X, Y, and Z) and an θ axis that rotates around the Z axis. The mirror mount is fixed on the Z-axis slide. Through programming control of the data processing and control components, this platform can drive the right-angle prism to perform three-dimensional spatial positioning with micron-level precision and adjust its horizontal yaw angle (θ axis) to align with the dispensing areas at different positions on the inner wall of the stator.

[0075] The active lighting assembly uses a blue LED line laser with a collimated emission plane. The laser is fixedly mounted so that the emitted line structured light can be projected onto the adhesive area on the inner wall of the VCM stator at an incident angle of approximately 30°.

[0076] The data processing and control component consists of an industrial computer and a motion control card. It runs dedicated measurement software to perform the following functions:

[0077] Motion control: Based on the preset VCM stator model, the corresponding detection program is called to automatically drive the mechanical adjustment component to position the right-angle prism to the inner cavity entrance, and then slowly insert it along the Z-axis until the incident right-angle surface of the prism is directly facing the glue area.

[0078] Image Acquisition and 3D Reconstruction: The CCD camera is controlled to continuously acquire images at a fixed frequency. Simultaneously, the Z-axis platform is controlled to drive the prism to perform longitudinal scanning at a constant speed. During this process, the line laser forms stripes on the adhesive surface that are deformed due to height, and these stripes are captured by the camera through the prism as a series of side-view contour images. The software processes the image sequence based on the principle of laser triangulation: first, the center line of the laser stripes in each frame is extracted; then, according to the calibration geometry of the camera and laser, the pixel position of the stripe center is converted into three-dimensional spatial point coordinates, and finally, the images are stitched together to form a three-dimensional point cloud of the adhesive area.

[0079] Feature Extraction and Judgment: In the 3D point cloud, the software first determines the uncoated inner wall surface as a predetermined reference plane based on the known stator inner wall model using a plane fitting algorithm. Then, a 0.5mm x 0.5mm square area is defined as a fixed test area around the theoretical center of the adhesive application. The vertical distance from all point clouds within this area to the reference plane is calculated, and the maximum value is identified as the height (Hmax) of the highest point on the adhesive surface. The preset acceptable height threshold is 0.15mm ± 0.03mm. If Hmax falls within this range, it is judged as "acceptable"; otherwise, it is "unacceptable".

[0080] System Calibration: The device is equipped with calibration components, including standard step blocks with three known heights of 0.10mm, 0.20mm, and 0.30mm. Before each shift of production, the calibration process is automatically executed: the step blocks are scanned and measured, the measured height values ​​are compared with the actual values, compensation coefficients are calculated and stored, and automatically applied in subsequent measurements to ensure long-term measurement accuracy better than ±0.005mm.

[0081] Workflow:

[0082] The VCM stator to be tested is transported to the testing station by a conveyor belt and precisely positioned.

[0083] The data processing and control component initiates the detection program and controls the mechanical adjustment component to move the optical probe (including the prism) to the stator end face.

[0084] The probe is inserted into the stator cavity along the Z-axis and moves to the position above the first adhesive dot according to the preset coordinates.

[0085] Turn on the line laser, control the probe to perform longitudinal scanning, and the CCD camera simultaneously acquires image sequences.

[0086] The software performs real-time 3D reconstruction, calculates the height H_max of the current adhesive application point, and immediately determines its suitability. If the application is unsatisfactory, the workpiece ID and defect information are recorded.

[0087] The probe moves to the next dispensing position until all dispensing positions on the workpiece have been inspected.

[0088] Once the probe is withdrawn, the downstream sorting mechanism will control the workpiece to be sent to the "qualified" or "unqualified" flow direction based on the final judgment result.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical measuring device for detecting the height of glue in a confined space, characterized in that, include: Imaging components, including a CCD camera and its lens; An optical steering assembly is disposed in front of the optical path of the lens. The assembly includes at least one right-angle prism, which is configured such that its incident right-angle surface receives an imaging beam from the glue area of ​​the workpiece being measured, and the beam undergoes total internal reflection on its inclined surface and exits from its exit right-angle surface, thereby achieving a 90° optical path deflection of the imaging beam. A mechanical adjustment assembly, connected to the optical steering assembly, is used to adjust at least the position and lateral yaw angle of the right-angle prism within the confined space; A data processing and control component is communicatively connected to the imaging component and the mechanical adjustment component; The data processing and control component is configured to perform the following operations: Control the mechanical adjustment assembly to drive the right-angle prism to a preset detection position; The imaging component is controlled to capture a sequence of images containing the side view contour of the glue area through the right-angle prism; The sequence of images is subjected to three-dimensional scanning and reconstruction processing to determine the fixed test area of ​​the glue area, and the height value of the highest point of the glue surface in the area relative to the predetermined reference plane is extracted. The qualification is determined based on the height value.

2. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, The optical steering component is a single right-angle prism, the overall size of which is designed to extend into the inner cavity of the coil winding of the VCM voice coil motor stator assembly, and the incident right-angle surface is directly opposite the glue area dotted on the inner wall of the stator.

3. The optical measuring device for detecting glue height in a confined space as described in claim 2, characterized in that, The device is used to detect the adhesive dispensing height on the side wall of the VCM stator. The predetermined reference surface is the uncoated plane of the inner wall of the stator. The data processing and control component automatically fits the reference surface by analyzing image or point cloud data.

4. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, The mechanical adjustment component includes a multi-dimensional precision motion platform, on which the right-angle prism is fixed by a mirror mount. The data processing and control component drives the multi-dimensional precision motion platform to achieve precise adjustment of the position of the right-angle prism in the X, Y, and Z directions and the angle around at least one rotation axis.

5. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, It also includes an active illumination component, which is arranged to project structured light or illumination light of a specific wavelength onto the adhesive area of ​​the workpiece under test, and the optical steering component together with the imaging component constitutes part of the light path that receives the illumination light after it is modulated by the adhesive surface and reflected.

6. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, In the data processing and control component, the operation of performing three-dimensional scanning and reconstruction processing on the sequence images, determining the fixed test area, and extracting the height value of the highest point specifically includes: Based on the sequence of images, the three-dimensional point cloud data of the glue area is reconstructed using triangulation or focused depth sounding. In the three-dimensional point cloud data, a rectangular or circular area corresponding to the theoretical center of glue application is defined as the fixed test area based on the preset workpiece coordinates. Calculate the Z coordinates of all points within the fixed test area, and identify the maximum value of the Z coordinates as the height of the highest point on the adhesive surface.

7. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, The optical design of the right-angle prism satisfies the following condition: at the target working distance, both its incident right-angle surface and its exit right-angle surface are located within the depth of field of the CCD camera lens, to ensure the capture of images with clear outlines.

8. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, It also includes a calibration component comprising a standard step block with a known height; the data processing and control component is configured to periodically control the device to image and measure the standard step block, and to compensate the height measurement algorithm for parameters based on the deviation between the measurement results and the known height.

9. The optical measuring device for detecting glue height in a confined space as described in claim 1, characterized in that, The data processing and control component is further configured to: extract the width or volume information of the glue area while extracting the height value of the highest point, and combine the height value to perform a multi-dimensional comprehensive quality judgment.

10. A method for online detection of glue height based on optical steering, characterized in that, The device applied to any one of claims 1-9 includes the following steps: S1, the optical probe with an integrated right-angle prism is positioned at the entrance of the space to be measured by a mechanical adjustment component; S2, control the mechanical adjustment component to place the right-angle prism inside the space and adjust its orientation so that the CCD camera can clearly image the area of ​​the adhesive to be tested through the prism; S3, drive the right-angle prism or the imaging component to perform scanning motion, while the CCD camera acquires a series of glue outline images obtained from different perspectives through the prism's rotation; S4, The series of images are reconstructed in three dimensions using an image processing algorithm, and a preset fixed test area is located in the reconstructed three-dimensional model; S5. Calculate the height of the highest point on the adhesive surface within the fixed test area, compare it with a preset qualified threshold, and output the test result to control product sorting.

Images