Method for rapidly detecting optical distortion of automobile front windshield
By using simple inspection tools and black-and-white diagonal stripe projection photographs to identify optical distortion in car windshields, the problem of rapid inspection has been solved, production costs have been reduced, and safety has been improved.
Patent Information
- Application Number
- CN202511170068.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-20
- Publication Date
- 2025-11-18
AI Technical Summary
Existing technologies make it difficult to quickly and cost-effectively detect optical distortion in automotive windshields, leading to high costs and safety hazards in production.
Optical distortion is detected using simple testing tools (testing lightbox, testing bracket, and camera or mobile phone). Optical distortion is identified by black and white diagonal stripe projection photos, and the degree of distortion is judged by the width of the white secondary image.
It enables rapid and low-cost optical distortion detection, avoiding the generation of defective products and large-scale glass scrapping, reducing production costs and improving safety.
Smart Images
Figure CN120970518A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to automotive windshields, and more specifically to a method for rapidly detecting optical distortion of automotive windshields. Background Technology
[0002] Modern car windshields are typically large, single-pane curved surfaces with a certain curvature. A windshield has four edges: the edge that contacts the roof is called the top edge, the edge opposite the top edge is called the bottom edge, and the other two edges are called the side edges. Currently, a significant portion of windshield bending is still completed in gravity forming furnaces, specifically utilizing the glass's own weight to bend and droop after heating. When using this process, sometimes the temperature difference between the ink-printed and non-ink-printed areas at the bottom of the glass is too large, resulting in issues at the screen-printed edge area at the bottom edge (the transition area between the ink-printed and non-ink-printed areas; the height of this area (the direction extending from the bottom edge to the top edge is called the height) is typically 50-70mm. Figure 1 The area within the center circle (shown in the image) often exhibits optical distortion. Drivers will experience discomfort when viewing the road ahead through a windshield with optical distortion defects. Therefore, if the optical distortion of the windshield is severe, it cannot be installed on the vehicle, rendering the glass unusable.
[0003] This type of optical distortion is difficult to detect using conventional inspection methods (such as perspective optics, lightbox inspection, fixture inspection, or simple visual observation). It often requires specialized inspection equipment (such as Powerview) or a professional inspection room with a projector. However, these methods have the following problems: ① The equipment is expensive, complex to operate, or time-consuming; ② These inspections are usually performed on the final inspection line before shipment, requiring all glass to be moved to the inspection room and then transported to the next process, increasing production costs; ③ Because it is usually performed on the final inspection line before shipment, even if the defect is detected, significant losses have often already occurred (it could be some products or the entire batch). If this defect is not detected, after installation on a car, drivers will often experience blurry or distorted images when observing objects through the silkscreened edge area at the bottom of the windshield, potentially affecting driving and posing a safety hazard.
[0004] To avoid losses due to large quantities of windshields being scrapped or even entirely due to defects only being detected on the final inspection line, it would be best to detect these defects quickly during the bending and forming process in the furnace. Currently, there is a lack of a low-cost, easy-to-operate, and rapid method for detecting optical distortion in windshields. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for quickly detecting optical distortion of a car windshield. The method is low in cost, easy to operate, and can quickly detect whether there is optical distortion in the windshield.
[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0007] A method for rapidly detecting optical distortion of automotive windshields includes the following steps:
[0008] 1) Prepare a testing light box and a testing bracket; the testing light box has two oppositely arranged front side panels and rear side panels, the front side panel is provided with a black and white diagonal striped curtain, and the inner wall of the rear side panel is provided with a light source;
[0009] 2) Place the testing bracket in front of the testing light box, and place the glass to be tested on the testing bracket with the convex side facing up and the top edge facing the testing light box. Then move the testing bracket so that the top edge of the glass to be tested is close to or in contact with the front side panel of the testing light box.
[0010] 3) The inspector stands directly in front of the glass to be inspected and takes a picture of the glass. The projected picture should show the whole picture of the glass and have clear black and white diagonal stripes.
[0011] 4) The inspector observes whether there is a shadow between white and black between the white and black stripes in the projected photograph. This shadow is called a white secondary image. If no white secondary image appears, it is determined that the glass under test does not have optical distortion (the manufacturer can continue mass production according to the current process); if a white secondary image appears, it is determined that the glass under test has optical distortion.
[0012] In practice, the inventors of this application, through repeated study and comparative analysis of the projections from a testing lightbox onto windshields with localized optical distortion defects and those without, discovered that the diagonal stripes projected onto windshields with optical distortion defects exhibit a gray shadow—a white secondary image—between white and black, in the form of a gray shadow between white and black. By visually estimating the width of this white secondary image, the extent of optical distortion in the windshield can be quickly determined to determine whether it is suitable for the next process. Furthermore, the following criteria are used to determine whether the glass to be tested can be used for the next process:
[0013] When the maximum width of one of the white secondary images is greater than or equal to half the width of the black stripe adjacent to it, the glass under inspection is judged to have a serious optical distortion defect and cannot be used for the next process; at the same time, mass production cannot continue according to the current process to avoid a large number of glass scraps.
[0014] When the maximum width of each white sub-image in all white sub-images is less than 1 / 2 of the width of the black stripe adjacent to it, it is determined that the glass under inspection has only a slight optical distortion defect and can be used for the next process; at the same time, it can continue to be mass-produced according to the current process.
[0015] In step 1) of the method described in this invention, the front panel of the detection lightbox is made of a transparent material, and the black and white striped curtain can be disposed on the inner wall or the outer wall of the front panel. Generally, the black and white striped curtain is approximately the same size as the front panel. When the length of the black and white striped curtain is 200cm and the height is 220cm, the width of both the black and white stripes is preferably 20-30cm, and the tilt angle of both the black and white stripes is preferably 40-50°. In a preferred embodiment, the width of both the black and white stripes is 25cm, and the tilt angle of both the black and white stripes is 45°.
[0016] The height of the testing bracket is related to the size of the testing light box and the size of the glass to be tested. The principle is that when the glass to be tested is placed on the testing bracket with its convex side facing upwards and its top edge facing the testing light box, and then the testing bracket is moved so that the top edge of the glass is close to or in contact with the front panel of the testing light box, when an observer stands at a certain distance in front of the glass and observes it, black and white diagonal stripe projections will be visible on the glass. The experience of the inventors' team shows that when the height of the testing bracket is 90-100cm, the length of the testing light box should be greater than the length of the glass to be tested, and the height of the testing light box is preferably greater than or equal to 200cm. In a preferred embodiment, the height of the testing bracket is 95cm, and the height of the testing light box is 220cm.
[0017] The light source provided on the inner wall of the rear panel can be an incandescent lamp or an LED lamp, and one or more lamps can be selected according to the brightness. Incandescent lamps are preferred. In a preferred embodiment, 6 to 7 30W incandescent lamps are selected and they are evenly distributed on the inner wall of the rear panel.
[0018] In step 2) of the method of the present invention, when moving the detection bracket, it is preferable to move the detection bracket so that the top edge of the glass to be inspected is in complete contact with the front panel of the detection light box; when moving the detection bracket so that the top edge of the glass to be inspected is close to the front panel of the detection light box, it is preferable to control the distance between the top edge of the glass to be inspected and the front panel of the detection light box to be less than or equal to 20 cm.
[0019] In step 3) of the method of the present invention, for a tester who is 1.5 to 1.8 meters tall, it is preferable that the tester stands on the extension line of the center line of the glass to be inspected and is 3.0 to 3.5 meters away from the glass to be inspected to take pictures.
[0020] Compared with the prior art, the present invention is characterized by:
[0021] 1. The method described in this invention can quickly detect and identify windshields with optical distortion using simple detection tools (detection light box, detection bracket, camera or mobile phone for taking pictures). The detection equipment is low in cost and the method is easy to operate, which reduces complicated detection and identification, avoids the continuous generation of unqualified products, and reduces the losses of manufacturing enterprises.
[0022] 2. In the method described in this invention, the testing tool is directly located in the bending and forming workshop. Testing can be carried out immediately after the glass bending and forming process is completed. When the test sample has severe optical distortion, the current production should be stopped immediately and the process adjusted to avoid a large loss of scrapped glass. On the other hand, since the testing is carried out in the bending and forming workshop, there is no need to move the windshield over a long distance, which further reduces production costs. Attached Figure Description
[0023] Figure 1 This is a diagram showing the markings for the silkscreened edge area at the bottom of the windshield.
[0024] Figure 2 This is a schematic diagram showing the placement of the testing light box, testing bracket, and glass under test when the optical distortion deformation of a certain model of glass produced by the applicant is detected using the method described in this invention in Example 1.
[0025] Figure 3 This is a schematic diagram of the standing position of the person taking a projection photograph using the method described in this invention in Example 1.
[0026] Figure 4 This is a comparison and evaluation image of the white secondary image and the black stripes in the projection photograph taken by the tester in Example 1.
[0027] Figure 5 The image shown is a projection photograph taken in Example 1 of the same type of glass to be tested using a professional testing laboratory.
[0028] Figure 6 The image shown is a projection photograph obtained by using the method described in this invention in Example 2.
[0029] Figure 7 The image shown is a projection photograph taken in Example 2 of the same type of glass to be tested using a professional testing laboratory. Detailed Implementation
[0030] To better explain the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the implementation of the present invention is not limited thereto.
[0031] In the following embodiment description, the glass to be inspected refers to the windshield product to be inspected, which has four edges. The edge that contacts the roof when installed on a vehicle is called the top edge, the edge opposite the top edge is called the bottom edge, and the remaining two edges are called the side edges. The distance between the bottom edge and the top edge is called the height of the glass to be inspected, and the distance between the two side edges is called the length of the glass to be inspected.
[0032] Example 1
[0033] A method for rapidly detecting optical distortion of automotive windshields includes the following steps:
[0034] 1) Prepare a testing light box and a testing bracket; the testing light box has two oppositely arranged front side panels and rear side panels, two oppositely arranged left side panels and right side panels, and a top panel. The front side panel is provided with a black and white diagonal striped curtain, and the inner wall of the rear side panel is provided with a light source.
[0035] The front panel of the testing lightbox is made of transparent material, with a black and white striped curtain tautly attached to its inner wall. The testing lightbox is 200cm long and 220cm high, supported on the ground by pillars, with a distance of 8.5cm between the front and rear panels. The black and white striped curtain is 200cm long and 220cm high, with both black and white stripes 25cm wide and tilted at 45° (based on the horizontal line). The testing bracket is 95cm high.
[0036] The inner wall of the rear panel is evenly equipped with six 30W incandescent lamps.
[0037] 2) Place the testing bracket in front of the testing light box, take the glass to be tested and place it on the testing bracket with the convex side facing up and the top edge facing the testing light box, and then move the testing bracket so that the edge of the top edge of the glass to be tested is in complete contact with the front side panel of the testing light box.
[0038] In this embodiment, the glass to be inspected is a windshield of model 7279 manufactured by the applicant.
[0039] 3) The inspector stands on the extension line of the center line of the glass to be inspected, at a distance of 3.0~3.5m from the glass to be inspected, and takes a picture of the glass. The projected picture should show the whole picture of the glass to be inspected, and the glass to be inspected should be covered with black and white diagonal stripes, and the black and white diagonal stripes should be clear.
[0040] 4) The inspector observes whether a shadow of color between white and black appears between the white and black stripes in the projected photograph. This shadow is called a white secondary image. If no white secondary image appears, the glass under inspection is determined to be free of optical distortion defects and can be used in the next process. If a white secondary image appears, the glass under inspection is determined to have optical distortion defects. When the glass under inspection has optical distortion, the following criteria are used to determine whether the glass can be used in the next process:
[0041] ① When the maximum width of one of the white secondary images is greater than or equal to 1 / 2 of the width of the black stripe adjacent to it, the glass to be inspected is judged to have a serious optical distortion defect and cannot be used for the next process;
[0042] ② When the maximum width of each white sub-image in all white sub-images is less than 1 / 2 of the width of the black stripe adjacent to it, it is determined that the glass under inspection has a slight optical distortion defect and can be used for the next process.
[0043] Figure 2 This is a schematic diagram showing the placement of the inspection light box, inspection bracket, and glass under inspection when performing optical distortion detection on a glass of model 7279 using the above method. Figure 3 A diagram illustrating the standing position of the person being photographed during the projection process. Figure 4 This is an evaluation image comparing the white secondary image and the black image in the projected photographs taken by the tester. Figure 4 It can be seen that the width of the white secondary image is greater than 1 / 2 of the width of the black stripe adjacent to it. Therefore, it is determined that the glass to be inspected has serious optical distortion (i.e., the glass to be inspected is unqualified) and cannot be used for the next process.
[0044] After completing the above tests, the glass sample of model 7279 was sent to the applicant's professional testing laboratory at the final inspection line before shipment for testing using a slide projector (testing and judgment were conducted according to the applicant's internal testing requirements and standards, the same below). The projected photos are as follows. Figure 5 As shown. The test results indicate that the minimum zebra deformation width is less than 6mm, therefore the glass under test is deemed unqualified. This is consistent with the test results obtained using the method described in this invention.
[0045] In addition, several other glass samples of the same model but different types were randomly selected and tested using the method described above and by sending them to a professional testing room at the final inspection line before leaving the factory for testing with the aid of a slide projector. The test results of the two methods were consistent.
[0046] Example 2
[0047] Repeat Example 1, but replace the glass to be inspected with a windshield of model 6564 produced by the applicant.
[0048] No white secondary image appeared in the final projected photograph (e.g.) Figure 6 As shown in the figure, it is determined that the glass to be inspected does not have optical distortion and can be used for the next process.
[0049] After completing the above tests, the glass of model 6564 was sent to the applicant's final inspection line's professional testing room for testing using a slide projector. The test results showed that the glass did not exhibit any optical distortion (such as...). Figure 7 As shown in the figure, the glass to be inspected is deemed qualified. This is consistent with the test results obtained using the method described in this invention.
Claims
1. A method for rapidly detecting optical distortion of a car windshield, comprising the following steps: 1) Prepare a testing light box and a testing bracket; the testing light box has two oppositely arranged front side panels and rear side panels, the front side panel is provided with a black and white diagonal striped curtain, and the inner wall of the rear side panel is provided with a light source; 2) Place the testing bracket in front of the testing light box, and place the glass to be tested on the testing bracket with the convex side facing up and the top edge facing the testing light box. Then move the testing bracket so that the top edge of the glass to be tested is close to or in contact with the front side panel of the testing light box. 3) The inspector stands directly in front of the glass to be inspected and takes a picture of the glass. The projected picture should show the whole picture of the glass and have clear black and white diagonal stripes. 4) The inspector observes whether there is a shadow between white and black between the white and black stripes in the projected photograph. This shadow is called a white secondary image. If no white secondary image appears, it is determined that the glass under test does not have optical distortion. If a white secondary image appears, it is determined that the glass under test has optical distortion.
2. The method according to claim 1, characterized in that, In step 4), when a white secondary image appears between the white and black stripes in the projected image, the width of the white secondary image is used to determine whether the glass to be inspected can be used in the next process. The judgment criteria are as follows: When the maximum width of one of the white secondary images is greater than or equal to half the width of the black stripe adjacent to it, the glass under inspection is judged to have severe optical distortion and cannot be used for the next process. When the maximum width of each white sub-image in all white sub-images is less than 1 / 2 of the width of the black stripe adjacent to it, it is determined that the glass under inspection has only slight optical distortion and can be used for the next process.
3. The method according to claim 1 or 2, characterized in that, In step 1), the black and white striped curtain has a width of 20-30cm for both the black and white stripes and an angle of 40-50° for both.
4. The method according to claim 3, characterized in that, The width of both the black and white stripes is 25cm, and the angle of inclination of the black and white stripes is 45°.
5. The method according to claim 1 or 2, characterized in that, In step 2), when the moving inspection bracket brings the top edge of the glass to be inspected close to the front panel of the inspection light box, the distance between the top edge of the glass to be inspected and the front panel of the inspection light box is controlled to be less than or equal to 20 cm.
6. The method according to claim 1 or 2, characterized in that, When the height of the testing bracket is 90~100cm, the height of the testing light box is greater than or equal to 200cm.
7. The method according to claim 1 or 2, characterized in that, When taking photos of the glass to be inspected, the inspector should stand 3.0 to 3.5 meters directly in front of the glass.