JP4010726B2 - Transparent panel inspection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection device for a flat transparent panel such as transparent glass, plastic or sheet.
[0002]
[Prior art]
A transparent panel, which is one of the main components such as a flat input device, may have defects such as scratches, dirt, dust, lint, or bubbles in the manufacturing stage. Such defect inspection for finding defects is indispensable for maintaining the trust of customers, but in the conventional inspection, it relies on the visual inspection of the inspector. In other words, by inspecting the transparent panel in a transparent manner or by tilting it with respect to the light source, the inspector confirms the reflection of light with the eye and grasps the presence or absence of defect defects and the contents of defect defects.
[0003]
[Problems to be solved by the invention]
Defects such as those described above have a wide variety of sizes, colors, etc., especially when they are flawed, and the depth, width, length, and direction are all different, and a great deal of effort is required to find them. And it takes time. In particular, in the inspection by the inspector, even if an inspection standard serving as a sample is prepared, the contents of the judgment are different for each inspector, and it is difficult to always maintain tension during a long work.
[0004]
Accordingly, an object of the present invention is to provide a transparent panel inspection apparatus that can easily detect various defects and can be easily structured regardless of the installation environment.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the transparent panel inspection apparatus according to the present invention, a transparent diffusion panel is provided in parallel with the surface of the transparent panel by irradiating the inspection panel with the inspection light and the transparent panel. Is provided on the opposite side of the ring-shaped diffuse illuminator, reflects the inspection light transmitted through the transparent panel and irradiates the transparent panel, and the ring-shaped diffuse illuminator on the opposite side of the transparent panel And a lens that transmits only light substantially parallel to the optical axis among the light scattered on the transparent panel and the light that is reflected by the reflecting mirror and then irradiated to the transparent panel.
[0006]
According to the present invention, since the diffused light is uniformly applied to the transparent panel to be inspected using the ring-shaped diffusing illuminator and the reflecting mirror, it is stable regardless of the type, shape and size of the defect defect. Thus, defect defects can be detected. In addition, by using a lens such as a telecentric lens, only light that is substantially parallel to the optical axis among light scattered on the transparent panel and light scattered on the transparent panel after being reflected by the reflecting mirror is transmitted. Since imaging is performed using an imaging means such as a CCD camera, the inspection can be performed stably without being affected by disturbances such as surrounding ceiling lights, and the installation environment of the inspection apparatus main body is not limited. Moreover, since a commercially available ring-shaped fluorescent lamp is applied as the ring-shaped diffuse lighting device, the structure is easy at low cost.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram illustrating a defect defect of a transparent panel.
FIG. 1 shows a cross section of a transparent panel 1 to be inspected. The structure thereof is a glass substrate 2 laminated with a film 3, and the thickness is usually about 3 mm, for example. When the transparent panel 1 is normal without defects, the flat surface is flat, and the front and back are cleaned and in a clean state before the defect inspection. During the manufacturing process, the glass substrate 2 and the film are in a clean state. 3 may be mixed with yarn waste 11, dust 12, dirt 13, or bubbles 14 for some reason, and scratches 15 may also be generated due to inadequate handling or the like. Such defect defects have various shapes and various curvatures, and the color may be light in addition to black and white. Further, in some cases, it is necessary to detect a defect defect having a size of about 50 μm. In particular, scratches have no regularity such as depth, width, length, and cause of occurrence.
[0008]
According to the transparent panel inspection apparatus of the present invention, it is possible to stably detect such a wide variety of defects. That is, in the transparent panel inspection apparatus according to the present invention, uniform inspection light is irradiated to the transparent panel, which is the inspection object, and the difference in light scattering in the transparent panel is extracted and captured as a black and white image, for example. Then, the presence / absence of defect defect and the type of defect are grasped from the contrast of black and white contrast of the obtained image. The intensity of the black and white contrast in the captured image becomes clearer by increasing the intensity of light applied to the transparent panel to be inspected, and only a predetermined component is extracted from the scattered light components. If the image is taken, it can be obtained as a clearer image.
[0009]
FIG. 2 is a view showing a transparent panel inspection apparatus according to the first embodiment of the present invention.
FIG. 2A is a plan view of the transparent panel inspection device 21, and FIG. 2B is a cross-sectional view of the transparent panel inspection device 21.
First, the configuration of the transparent panel inspection apparatus 21 according to the first embodiment of the present invention will be described. The transparent panel inspection device 21 includes a ring-shaped diffuse illumination tool 22, a reflecting mirror 23, a lens 24, and an imaging unit 25.
[0010]
The ring-shaped diffuse lighting device 22 is provided in parallel to the surface of the transparent panel 1 to be inspected. The ring-shaped diffuse lighting fixture 22 may be a commercially available ring-shaped fluorescent lamp, and examples of the dimension include a diameter of 110 mm or 127 mm.
The reflecting mirror 23 is provided on the opposite side to the ring-shaped diffuse lighting device 22 with respect to the transparent panel 1 (not shown in FIG. 2A).
[0011]
The lens 24 is provided on the side opposite to the transparent panel 1 with respect to the ring-shaped diffuse lighting device 22 so that the center of the lens 24 and the center of the ring-shaped diffuse lighting device 22 are concentric. The lens 24 collects light scattered on the transparent panel 1 and light scattered on the transparent panel 1 after being reflected by the reflecting mirror 23. In this embodiment, the angle of view is on both sides of the lens. A telecentric lens is used in which the principal ray on both sides of the lens is 0 °, ie parallel to the principal axis.
[0012]
The imaging means 25 is provided on the opposite side of the lens 24 with respect to the ring-shaped diffuse illumination tool 22, but the center of the imaging means 25 is concentric with the center of the ring-shaped diffuse illumination tool 22. Examples of the imaging unit 25 include a CCD camera and a MOS camera.
Note that the inspection range of the transparent panel inspection apparatus 21 according to the present embodiment depends on the image pickup possible range of the image pickup means 25, but since the size of the transparent panel 1 to be inspected varies, the entire transparent panel 1 is covered. In order to perform the inspection, the transparent panel inspection device 21 may be further provided with a moving means that can move in the horizontal direction.
[0013]
Next, the operation principle of this embodiment will be described.
The inspection light diffused from the ring-shaped diffused illumination tool 22 shown in FIG. 2 is scattered in various directions when it reaches the transparent panel 1, but in this embodiment, it is scattered particularly in a place where a defect defect exists. Based on the fact that light is biased, this is imaged by the imaging means 25, and the presence / absence of a defect defect and the type of defect defect are grasped from the intensity of black and white contrast in the obtained image.
[0014]
FIG. 3 is a diagram for explaining the operating principle of the first embodiment of the present invention.
FIG. 3A shows light scattering when foreign matter 41 such as lint, dust, and dirt is mixed into the transparent panel 1 as a defective defect, and FIG. 3B shows a scratch on the transparent panel 1 as a defective defect. The scattering of light when 42 occurs is shown.
As shown in FIGS. 3A and 3B, when the transparent panel 1 is irradiated with the inspection light 31 uniformly emitted from the ring-shaped diffuse illuminator 22, on the surface of the transparent panel 1 where there is no defect. A part of the inspection light 31 is reflected (reflected light 32) and a part is transmitted (transmitted light 33). The transmitted light 33 is reflected by the reflecting mirror 23 and is again irradiated on the transparent panel 1 and passes through the transparent panel 1 (transmitted light 34).
[0015]
Since the inspection light 31 is emitted uniformly from the ring-shaped diffuse lighting device 22 with respect to the direction and the light intensity, the reflected light 32 and the transmitted light 34 in the transparent panel 1 are obtained at a normal position where there is no defect in the transparent panel 1. And the ratio of the generation of the reflected light 32 and the transmitted light 34 are almost uniform, and the scattering is almost free from bias.
However, when the transparent panel has the foreign matter 41 as shown in FIG. 3A or the scratch as shown in FIG. 3B, the light scattering at the location is biased as described below. That is, as shown in FIG. 3A, when the inspection light 31a is irradiated to a place where the foreign matter 41 exists, the film 3 is not flat at the place, so that the direction in which the inspection light 31 is reflected is disturbed (reflection) Light 32a). In particular, when the foreign matter 41 is yarn waste or the like, the transmission of light is hindered at the location, and the ratio of generation of the reflected light 32 and the transmitted light 33 is also different from the location where there is no defect. Further, when the transmitted light 33 is reflected by the reflecting mirror 23 and applied to the end of the foreign material 41, the refractive index changes due to the presence of the foreign material 41, but the light is transmitted with the refractive index (transmitted light 34a). . As described above, in the portion where the foreign matter 41 exists, the light scattering is biased.
[0016]
Further, as shown in FIG. 3B, when the inspection light 31b is irradiated to a place where the scratch 42 is present, the direction in which the inspection light 31b is reflected is disturbed (reflection) because the film 3 is not flat at the place. Light 32b). In addition, when the transmitted light 33 is irradiated to a place where the post-reflection scratch 42 exists by the reflecting mirror 23, the light is transmitted through the scratch 42 in a direction different from the flat surface (transmitted light 34b). As described above, even in a place where the scratch 42 is present, the light scattering is biased as in the case where the foreign matter 41 is present.
[0017]
As described above, the scattered light is biased at the location where the defect is present. Taking light parallel to the normal line of the transparent panel 1 as an example, the light reflected or transmitted at a place where there is no defect on the transparent panel 1 and the light reflected or transmitted at a place where a defect exists are scattered. The ratio of the light parallel to the normal line of the transparent panel 1 included in the entire light is different. That is, for the diffused light uniformly emitted from the ring-shaped diffuse lighting device 22, the light is uniformly reflected or transmitted at a position where there is no defect on the transparent panel 1, but at a place where there is a defect. As a result, the light component parallel to the normal line of the transparent panel 1 changes.
[0018]
Therefore, in this embodiment, the light component that is substantially parallel to the normal line of the transparent panel 1 among the light scattered on the transparent panel 1 and the light that is reflected by the reflecting mirror 23 and then irradiated to the transparent panel 1 is scattered. Extract only. If this is picked up as a black and white image by the image pickup means 25 such as a CCD camera, the result is that white is emphasized as there are more components substantially parallel to the normal of the transparent panel 1.
[0019]
As the lens 24 for obtaining such a black and white contrast more clearly, in this embodiment, the telecentric angle of view is 0 ° on both sides of the lens, that is, the principal ray on both sides of the lens is parallel to the principal axis. Use a lens. FIG. 4 is an explanatory diagram of a telecentric lens used in the present invention. FIG. 4A shows a normal lens, and FIG. 4B shows a telecentric lens.
[0020]
As shown in FIG. 4A, in a normal lens, the principal ray 51 forms an image by being incident on the lens 24 with a predetermined angle of view θ, whereas in a telecentric lens, the principal ray 51 is shown in FIG. As shown, the field angle on both sides of the lens is 0 °, that is, the principal ray 51 on both sides of the lens is parallel to the principal axis. That is, the chief ray that contributes to image formation is parallel to the principal axis. In other words, it can be said that the telecentric lens has a function of extracting and emitting only light rays parallel to the principal axis among the incident light rays.
[0021]
In this embodiment, a telecentric lens is used as the lens 24, as shown in FIG. 2, on the side opposite to the transparent panel 1 with respect to the ring-shaped diffuse lighting device 22, and the center of the lens 24 and the center of the ring-shaped diffuse lighting device 22. Of the light scattered on the transparent panel 1 and the light scattered on the transparent panel 1 after being reflected by the reflecting mirror 23 and transmitted substantially parallel to the optical axis. .
[0022]
The light transmitted through the lens 24 is imaged by the imaging means 25. In this embodiment, a CCD camera is used as the imaging means 25, but a MOS camera or the like may be used. FIG. 5 is a diagram showing a test result in the transparent panel inspection apparatus according to the first embodiment of the present invention. This figure is an optical condition with an optical magnification of 0.345, a field size of 25 mm × 20 mm, captured by a CCD camera under a diaphragm 2.5, and then digitally processed as a binary image, indicated by an arrow in the figure. The white part is defective. 5A shows scratches, FIG. 5B shows lint, FIG. 5C shows bubbles, and FIG. 5D shows black dust. From these figures, transparent panel inspection according to the present invention is shown. It can be confirmed that a defect can be detected by the apparatus.
[0023]
As described above, the inspection results regarding the transparent panel obtained by the transparent panel inspection apparatus according to the first embodiment of the present invention can be easily converted into a database through various digital processes and further effectively utilized.
As described above, according to the first embodiment of the present invention, since the diffused light is uniformly applied to the transparent panel to be inspected using the ring-shaped diffuse illuminator and the reflecting mirror, the defect is defective. It is possible to detect defect defects stably regardless of the type, shape, and size. In addition, by using a lens such as a telecentric lens, only light that is substantially parallel to the optical axis out of light scattered on the transparent panel and light scattered on the transparent panel is guided, and an imaging means such as a CCD camera is provided. Therefore, the inspection can be performed stably without being affected by disturbances such as surrounding ceiling lights, and the installation environment of the inspection apparatus main body is not limited. Moreover, since a commercially available ring-shaped fluorescent lamp is applied as the ring-shaped diffuse lighting device, the structure is easy at low cost.
[0024]
In order to improve the black-and-white contrast of the image obtained through the lens and improve the detection accuracy of defect defects, the intensity of the diffused light applied to the transparent panel is increased, and the light diffusion is more uniform. And it is sufficient. For example, if so-called quasi-Lambertian illumination is used to generate diffused light that irradiates the transparent panel, the light intensity and diffusivity can be further increased.
[0025]
The second embodiment of the present invention is proposed to further increase the light intensity and diffusivity compared to the first embodiment, and a plurality of ring-shaped diffuse lighting fixtures are installed.
FIG. 6 is a view showing a transparent panel inspection apparatus according to a second embodiment of the present invention.
6A is a plan view of the transparent panel inspection apparatus 51, and FIG. 6B is a cross-sectional view of the transparent panel inspection apparatus 51.
[0026]
In this embodiment, the ring-shaped diffuse lighting fixture 22 of the transparent panel inspection apparatus 21 in FIG. 2 is replaced with a plurality of ring-shaped diffuse lighting fixtures. In FIG. 6, three ring-shaped diffuse lighting fixtures 22a and 22b are used. 22c is illustrated.
In the present embodiment, a virtual hemispherical surface whose opening surface is parallel to the transparent panel 1 is assumed, and the ring diameters of the ring-shaped diffuse lighting fixtures 22a, 22b, and 22c become smaller as the distance from the transparent panel 1 increases on the virtual hemispherical surface. By stacking as many layers as possible, the same lighting effect as the quasi-Lambertian illumination can be obtained.
[0027]
As shown in FIG. 6, in this embodiment, assuming a hemispherical surface having a radius of 70 mm, for example, the upper surface of the transparent panel 1 to be inspected is arranged at a position corresponding to the opening surface of the virtual hemispherical surface. Is done. Note that the assumed radius of the virtual hemispherical surface is not limited to this, but it is preferable to assume a radius such that a commercially available ring-shaped fluorescent lamp can be applied as the ring-shaped diffuse lighting fixture.
[0028]
For example, the first ring-shaped diffuse lighting fixture 22a having a ring diameter of 134 mm above the upper surface of the transparent panel 1 is 49 mm above the upper surface of the transparent panel 1 so that each ring-shaped diffuse lighting fixture is arranged on the virtual hemispherical surface. The second ring-shaped diffused illuminator 22b with a ring diameter of 127 mm is stacked in layers with a third ring-shaped diffused illuminator 22c with a ring diameter of 100 mm above 99 mm. The lighting effect is almost the same as that of Lambert lighting. Commercially available ring-shaped fluorescent lamps may be used as the ring-shaped diffuse lighting fixtures 22a, 22b, and 22c. In the present embodiment, three ring-shaped diffuse lighting fixtures are used, but the number of ring-shaped diffuse lighting fixtures is not limited to this, and ring-shaped diffuse lighting fixtures having a predetermined ring diameter, Any number may be used as long as it is installed at a position that constitutes a virtual hemispherical surface.
[0029]
The reflecting mirror 23 is installed 30 mm below the upper surface of the transparent panel 1. (Not shown in FIG. 6A).
In the lens 24, the center of the lens 24 and the center of each ring-shaped diffuse lighting 22a, 22b, 22c are concentric on the opposite side of the transparent panel 1 with respect to each ring-shaped diffuse lighting 22a, 22b, 22c. It is provided as follows. The lens 24 collects light scattered on the transparent panel 1 and light scattered on the transparent panel 1 after being reflected by the reflecting mirror 23, and in this embodiment, the angle of view is formed on both sides of the lens. Is used, that is, a telecentric lens in which the principal rays on both sides of the lens are parallel to the principal axis.
[0030]
The imaging means 25 is provided on the opposite side of the lens 24 with respect to each ring-shaped diffuse lighting fixture 22a, 22b, 22c, but the center of the imaging means 25 is concentric with the center of each ring-shaped diffuse lighting fixture 22a, 22b, 22c. It is. Examples of the imaging means include a CCD camera and a MOS camera.
Note that the inspection range of the transparent panel inspection apparatus 21 according to the present embodiment depends on the image pickup possible range of the image pickup means 25, but since the size of the transparent panel 1 to be inspected varies, the entire transparent panel 1 is covered. In order to perform the inspection, the transparent panel inspection device 21 may be further provided with a moving means that can move in the horizontal direction.
[0031]
As described above, in this embodiment, a virtual hemispherical surface whose opening surface is parallel to the transparent panel is assumed, and the ring diameters of the plurality of ring-shaped diffuse illuminators become smaller as the distance from the transparent panel increases on the virtual hemispherical surface. Multi-layer stacking increases the light intensity and diffusivity of the diffused light that irradiates the transparent panel, so that the black-and-white contrast of the image obtained through the lens can be sharpened and the defect defect detection accuracy can be improved. it can.
[0032]
In this embodiment, since a commercially available ring fluorescent lamp can be applied as the ring-shaped diffuse lighting device, it is possible to obtain an illumination effect substantially equivalent to that of quasi-Lambertian illumination at a low cost.
[0033]
【The invention's effect】
As described above, according to the present invention, in the transparent panel inspection apparatus, the transparent panel to be inspected is uniformly irradiated with the diffused light using the ring-shaped diffuse illuminator and the reflecting mirror. It is possible to detect defect defects stably regardless of the type, shape, and size. In addition, by using a lens such as a telecentric lens, only light that is substantially parallel to the optical axis among light scattered on the transparent panel and light scattered on the transparent panel after being reflected by the reflecting mirror is transmitted. Since imaging is performed using an imaging means such as a CCD camera, the inspection can be performed stably without being affected by disturbances such as surrounding ceiling lights, and the installation environment of the inspection apparatus main body is not limited. Moreover, since a commercially available ring-shaped fluorescent lamp is applied as the ring-shaped diffuse lighting device, the structure is easy at low cost.
[0034]
Further, in the transparent panel inspection apparatus, when a plurality of ring-shaped diffuse illuminators are used, a virtual hemispherical surface whose opening surface is parallel to the transparent panel is assumed, and a plurality of the diffused lighting fixtures as the distance from the transparent panel increases on the virtual hemispherical surface Stacking the ring-shaped diffuse lighting fixtures so that the ring diameter is reduced increases the light intensity and diffusivity of the diffused light that irradiates the transparent panel, making the black and white contrast of the image obtained through the lens clearer. In addition, the defect defect detection accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a defect defect of a transparent panel.
FIG. 2 is a view showing a transparent panel inspection apparatus according to a first embodiment of the present invention.
FIG. 3 is a diagram for explaining the operation principle of the first embodiment of the present invention.
FIG. 4 is an explanatory diagram of a telecentric lens used in the present invention.
FIG. 5 is a view showing a test result in the transparent panel inspection apparatus according to the first embodiment of the present invention.
FIG. 6 is a view showing a transparent panel inspection apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Transparent panel 2 ... Glass substrate 3 ... Film 21, 51 ... Transparent panel inspection apparatus 22, 22a, 22b, 22c ... Ring-shaped diffused illumination tool 23 ... Reflector 24 ... Lens 25 ... Imaging means

Claims (2)

Irradiating inspection light onto a transparent panel, which is an object to be inspected, and a ring-shaped diffuse lighting device provided parallel to the surface of the transparent panel;
A reflective mirror that is provided on the opposite side of the ring-shaped diffuse lighting device with respect to the transparent panel, reflects the inspection light transmitted through the transparent panel, and irradiates the transparent panel;
Provided on the opposite side of the transparent panel with respect to the ring-shaped diffuse illuminator, among the light scattered on the transparent panel and the light scattered on the transparent panel after being reflected by the reflecting mirror, A lens that transmits only light substantially parallel to the optical axis ;
An imaging unit that is provided on the opposite side of the ring-shaped diffuse lighting device with respect to the lens, and that images the light transmitted through the lens;
A transparent panel inspection apparatus comprising:   The ring-shaped diffuse lighting device has at least one multilayer stack on a virtual hemispherical surface whose opening surface is parallel to the transparent panel so that the ring diameter of the ring-shaped diffuse lighting device decreases as the distance from the transparent panel increases. The transparent panel inspection apparatus according to claim 1.

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