Folding screen stress optical detection system

Abstract

The invention provides a folding screen stress optical detection system, and belongs to the field of intelligent optical detection.The folding screen stress optical detection system comprises an optical detection station, a detection carrying table line and a processor, a backlight source is arranged on the detection carrying table line, and the optical detection station is used for collecting folding screen images bent to different degrees on the detection carrying table line below; the processor receives the folding screen image collected by the optical detection station and analyzes and obtains the stress change of the folding screen bent to a corresponding degree; according to the non-contact optical detection scheme, mechanical damage to products is reduced, residual stress distribution of key parts such as a bending area of the folding screen can be accurately identified, key data are provided for reliability evaluation of the products, and the qualified rate of the folding screen is ensured. The diaphragm is convenient to popularize and apply in scenes related to diaphragms in the 3C fields of mobile phones, tablet computers, laptops and the like.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent optical detection, and particularly relates to a stress optical detection system for a folding screen. Background Art

[0002] With the development of technology, the manufacturing precision and requirements for the display screens of 3C products (computers, communications, and consumer electronics) are getting higher and higher. Currently, folding screen mobile phones are becoming more and more well-known and accepted by the general consumers, and the quality of folding screens, especially the detection problem of crease life, has received the most attention.

[0003] Traditional stress detection often requires the use of force sensors, etc. However, for folding screens, it is not easy to externally attach stress gauges, so contact detection methods cannot be used.

[0004] Therefore, it is necessary to find a non-contact detection method to achieve the stress life detection of folding screens. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a stress optical detection system for a folding screen, which can solve the above problems.

[0006] Design principle: The birefringence phenomenon is due to stress causing a change in the refractive index of the material, resulting in anisotropy. This belongs to the photoelastic effect, that is, stress birefringence. In a folding screen, the stress at the crease will cause lattice distortion of the material, thereby changing the refractive index and forming a birefringence phenomenon. First, when the folding screen material (such as transparent polyimide CPI or ultra-thin glass UTG) is repeatedly bent, local stress is generated in the hinge area, causing lattice distortion of the material, making the originally isotropic medium exhibit refractive index directional differences, forming a birefringence effect. Specifically, the CPI substrate is prone to deep creases, and there are still traces in the rotating shaft part of the UTG. Second, uneven stress distribution will cause the incident light to be decomposed into two polarized lights with perpendicular vibration directions and different propagation speeds. The phase difference (optical path difference) between the two is positively correlated with the stress magnitude. Therefore, birefringence detection can be used to evaluate the stress distribution of these materials during folding. Based on the industrial vision scenario, only the image of the corresponding crease area or the entire surface area needs to be optically collected, and the stress change of the folding screen can be evaluated through image processing technology, thereby reflecting the folding screen life corresponding to different bending degrees.

[0007] System design: The optical detection system of the folding screen is composed of two parts: a loading line and an optical detection station. At the same time, it should be able to meet the requirements that all four sides of the folding screen and the folding hinge, that is, the crease, can be detected. The overall design scheme is as follows.

[0008] A folding screen stress optical detection system includes an optical detection station, a detection stage line, and a processor. A backlight is provided on the detection stage line. The optical detection station is used to collect images of the folding screen with different degrees of bending on the detection stage line below, and the processor receives the folding screen images collected by the optical detection station and analyzes to obtain the stress change of the folding screen with the corresponding degree of bending.

[0009] Further, the optical detection station includes multiple groups of detection cameras and a top suction lifting mechanism arranged on the detection rack; multiple groups of the detection cameras collect different areas of the folding screen below, and at least one top suction lifting mechanism is used for the adsorption and lifting of the folding screen below.

[0010] Further, the top suction lifting mechanism includes a top suction lifting module, a suction plate adapter, a floating suction plate module, and a floating limit component; the floating suction plate module is connected to the lifting moving end of the top suction lifting module through the suction plate adapter, and the floating suction plate module forms a buffer stroke during the contact with the folding screen through the floating limit component to prevent hard contact from damaging the folding screen.

[0011] Further, the detection stage line includes a first stage and a second stage arranged on the driving stage line. Both stages include a structural suction plate, a leveling mechanism, and a stage frame. The two stage frames are connected to the moving top plate of the driving stage line; among them, the structural suction plate of the first stage is a male-engraved "day" - shaped suction plate, and the structural suction plate of the second stage is a female-engraved "day" - shaped suction plate or two rectangular suction plates arranged side by side at intervals.

[0012] Further, the stage frame of the first stage is a fixed bottom frame, while the stage frame of the second stage adopts a rotary drive for driving the horizontal rotation of the structural suction plate and the leveling mechanism of the second stage.

[0013] Further, a backlight is also provided between the structural suction plate and the leveling mechanism.

[0014] Further, the folding screen stress optical detection system further includes a loading module and a visual positioning module for picking up and positioning the product and then placing it on the detection stage line.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the non-contact optical detection solution of this application, the mechanical damage to the product is reduced, and the residual stress distribution of key parts such as the bending area of the folding screen can be accurately identified, providing key data for the reliability evaluation of the product and ensuring the qualification rate of the folding screen. It is convenient for popularization and application in scenarios involving diaphragms in the 3C fields such as mobile phones, tablets, and laptops. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 and Figure 2 are schematic diagrams of different embodiments of the folding screen stress optical detection system of the present invention; Figure 3 and Figure 4 is a schematic diagram of an optical inspection station with three rows of cameras; Figure 5 is a schematic diagram of an optical inspection station with two rows of cameras; Figure 6 is a schematic diagram of a top-suction lifting mechanism for small products without a rotation function; Figure 7 is a schematic diagram of a top-suction lifting mechanism for large products with a rotation function; Figure 8 and Figure 9 are schematic diagrams of different examples of the detection stage line.

[0017] In the figure: 100, optical inspection station; 110, inspection rack; 120, inspection camera; 130, top-suction lifting mechanism; 131, top-suction lifting module; 132, suction plate adapter; 133, floating suction plate module; 134, floating limit component; 135, top-suction rotation module; 200, detection stage line; 210, drive stage line; 220, first stage; 230, second stage; 231, structural suction plate; 232, leveling mechanism; 233, stage rack; 234, backlight; 240, stage adapter bottom plate; 300, loading module; 400, vision positioning module. Specific embodiments

[0018] 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 in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] The foldable screen stress optical detection system, see Figures 1-9 , includes an optical inspection station 100, a detection stage line 200, a loading module 300, a vision positioning module 400, and a processor. The loading module 300 and the vision positioning module 400 are used to pick up and position the product and then place it on the detection stage line 200. A backlight is provided on the detection stage line 200. The optical inspection station 100 is used to collect images of the foldable screen with different degrees of bending on the detection stage line 200 below. The processor receives the foldable screen images collected by the optical inspection station 100 and analyzes to obtain the stress changes of the foldable screen with corresponding degrees of bending.

[0020] Among them, the optical inspection station 100 includes multiple groups of inspection cameras 120 and a top suction lifting mechanism 130 arranged on the inspection frame 110; the multiple groups of inspection cameras 120 collect different areas of the lower folding screen, and at least one top suction lifting mechanism 130 is used for adsorbing and lifting the lower folding screen.

[0021] A plurality of arc-shaped grooves are formed on the inspection frame 110 for adjustably mounting the inspection cameras 120 in terms of position and angle.

[0022] The multiple groups of inspection cameras 120 include area array cameras and line array cameras, which are used to detect the crease area and the entire surface area of the folding screen.

[0023] In one example, for large products, the system includes two groups of inspection cameras 120. The first group of inspection cameras has three cameras, which collect the side surface area images of 2 / 5 of the two folding screens and the crease in the middle, that is, the bending area image. The second group of inspection cameras then captures the surface area images of the remaining 3 / 5 of the folding screen.

[0024] In another example, for small products, the system includes three groups of inspection cameras 120. The first group and the second group of inspection cameras use line array cameras. Among them, the first group of inspection cameras collects the images of the two long sides of the folding screen; at the second group of inspection cameras, the folding screen needs to be rotated 90°, and the two short sides and the middle crease of the folding screen are collected; the third group of inspection cameras uses an area array camera to collect the surface area image of the entire folding screen. It can take both defect detection and stress life detection into account.

[0025] The top suction lifting mechanism 130 includes a top suction lifting module 131, a suction plate adapter 132, a floating suction plate module 133 and a floating limit component 134; the floating suction plate module 133 is connected to the lifting moving end of the top suction lifting module 131 through the suction plate adapter 132, and the floating suction plate module 133 forms a buffer stroke during the contact with the folding screen through the floating limit component 134 to prevent hard contact from damaging the folding screen.

[0026] Furthermore, the top suction lifting mechanism 130 further includes a top suction rotation module 135, and the top suction rotation module 135 is arranged on the suction plate adapter 132 and is drivingly connected to the floating suction plate module 133 to rotate.

[0027] Among them, the top suction lifting module 131 can be in the form of a lifting cylinder, a linear motor, a motor screw rod, etc. Here, a lifting cylinder is preferably used for lifting drive. The suction plate adapter 132 is an L-shaped adapter plate. The vertical plate is connected to the moving end of the top suction lifting module 131, and the horizontal plate is used to directly or indirectly connect the floating suction plate module 133. When it is an indirect connection, the top suction rotation module 135 is arranged here, and then the top of the floating suction plate module 133 is connected to the rotation drive end of the top suction rotation module 135.

[0028] The floating suction plate module 133 has different models available for replacement to match folding screens of different sizes and specifications. The top suction rotation module 135 can be a rotary motor, a rotary cylinder, etc.

[0029] Among them, referring to Figure 8 , the detection stage line 200 includes a first stage 220 and a second stage 230 provided on the drive stage line 210. Both stages include a structural suction plate 231, a leveling mechanism 232, and a stage frame 233. The two stage frames 233 are connected to the movable top plate of the drive stage line 210; among them, the structural suction plate 231 of the first stage 220 is a male-engraved "day" - shaped suction plate, and the structural suction plate 231 of the second stage 230 is a female-engraved "day" - shaped suction plate or two rectangular suction plates arranged side by side at intervals.

[0030] Furthermore, the stage frame 233 of the first stage 220 is a fixed bottom frame, while the stage frame 233 of the second stage 230 uses a rotary drive to drive the structural suction plate 231 and the leveling mechanism 232 of the second stage 230 to rotate horizontally.

[0031] In a specific example, the first stage 220 and the second stage 230 are connected to the only movable top plate of the drive stage line 210 through the same stage adapter bottom plate 240; of course, the drive stage line 210 can have two movable top plates, and the first stage 220 and the second stage 230 are directly provided on the corresponding movable top plates without the need for an additional stage adapter bottom plate 240.

[0032] Of course, both stage frames 233 can also be fixed, and then a top suction lifting mechanism 130 with a top suction rotation module 135 needs to be used correspondingly.

[0033] A backlight 234 is also provided between the structural suction plate 231 and the leveling mechanism 232.

[0034] Referring to Figure 9 , it is also possible not to use the structural suction plate 231 with a "day" - shaped layout, and it can also be multiple structural suction plate blocks, which are combined side by side at intervals to realize image acquisition and non - acquisition of the crease of the folding screen, that is, the bending area (because light cannot be transmitted at the support of the structural suction plate 231, and it is inevitable to complete the splicing of the entire image or the acquisition of a specific area in steps).

[0035] For the example of the above - mentioned detection system, the quantitative relationship between the optical image information and the stress of the folding screen can be directly determined through optical information, such as the light intensity distribution or the front - and - back change after passing through the folding screen, and the material stress - optical constant of the folding screen itself.

[0036] Not shown in the figure, a laser source module that emits linearly or circularly polarized light is further provided on the detection rack 110, and the polarized light is arranged towards the folding screen on the detection stage line 200. The corresponding optical detection station 100 uses a photonic crystal polarizing inductor to convert polarization information into an image, and cooperates with the image processing software of the processor to generate a stress distribution heat map, realizing the visual analysis of the stress in the entire area of the folding screen.

[0037] The specific method is as follows: First, estimate the optical path difference. Specifically, after passing through the folding screen, elliptically polarized light is formed due to stress birefringence; by rotating the analyzer or the photonic crystal sensor, the change in polarization state is detected to calculate the optical path difference Δ. Secondly, determine the quantitative relationship between the optical path difference and the stress. According to the stress-optics law, the optical path difference Δ is proportional to the material thickness h and the principal stress difference (σ1 - σ2), that is, Δ = C·h·(σ1 - σ2); where C is the material stress-optical constant, which can be determined through existing calibration experimental data.

[0038] Of course, it is also possible to use an existing stress meter to synchronously record parameters such as light intensity and polarization rotation angle through a computer, and directly output the stress magnitude and principal stress direction data in combination with a mathematical model.

[0039] Through the detection scheme of the present application, non-contact measurement can be achieved, reducing mechanical damage to the product, and accurately identifying the residual stress distribution in key parts such as the bending area of the folding screen, providing key data for product reliability evaluation, and ensuring the qualification rate of the folding screen.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A folding screen stress optical detection system, characterized by: The folding screen stress optical detection system comprises an optical detection station (100), a detection platform line (200) and a processor, wherein a backlight source is provided on the detection platform line (200), the optical detection station (100) is used to collect images of folding screens bent to different degrees on the detection platform line (200) below, and the processor receives the folding screen images collected by the optical detection station (100) and analyzes and obtains stress changes of the folding screen corresponding to the bending degree.

2. The folding screen stress optical detection system according to claim 1, characterized in that: The optical inspection station (100) comprises a plurality of groups of inspection cameras (120) and a top suction lifting mechanism (130) arranged on an inspection frame (110); the plurality of groups of inspection cameras (120) collect data from different areas of a folding screen below, and at least one top suction lifting mechanism (130) is used for adsorbing and lifting the folding screen below.

3. The folding screen stress optical detection system according to claim 2, characterized in that: The plurality of groups of detection cameras (120) include area array cameras and line array cameras, and are used to detect the crease area and the entire surface area of ​​the folding screen.

4. The folding screen stress optical detection system according to claim 2, characterized in that: The top suction lifting mechanism (130) comprises a top suction lifting module (131), a suction plate adapter (132), a floating suction plate module (133) and a floating limit assembly (134); the floating suction plate module (133) is connected to the lifting movable end of the top suction lifting module (131) via the suction plate adapter (132); the floating suction plate module (133) forms a buffer stroke during contact with the folding screen via the floating limit assembly (134), thereby preventing the folding screen from being damaged by hard contact.

5. The folding screen stress optical detection system according to claim 4, characterized in that: The top suction lifting mechanism (130) further comprises a top suction rotating module (135), wherein the top suction rotating module (135) is arranged on the suction plate adapter (132) and drives the floating suction plate module (133) to rotate.

6. The folding screen stress optical detection system according to claim 4, characterized in that: The detection stage line (200) comprises a first stage (220) and a second stage (230) arranged on a driving stage line (210), the two stages each comprising a structural suction plate (231), a leveling mechanism (232) and a stage frame (233), the two stage frames (233) being connected to a movable top plate of the driving stage line (210); wherein the structural suction plate (231) of the first stage (220) is a positively engraved "sun"-shaped suction plate, and the structural suction plate (231) of the second stage (230) is a negatively engraved "sun"-shaped suction plate or two rectangular suction plates arranged side by side with a spacing.

7. The folding screen stress optical detection system according to claim 6, characterized in that: The platform frame (233) of the first platform (220) is a fixed base frame, while the platform frame (233) of the second platform (230) adopts a rotary driver for driving the structural suction plate (231) and the leveling mechanism (232) of the second platform (230) to rotate horizontally.

8. The folding screen stress optical detection system according to claim 6, characterized in that: A backlight source (234) is also provided between the structural suction plate (231) and the leveling mechanism (232).

9. The folding screen stress optical detection system according to claim 1, characterized in that: The folding screen stress optical detection system also includes a loading module (300) and a visual positioning module (400), which are used to pick up and position the product and then place it on the detection platform line (200).

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