KR100945444B1 - Apparatus and Method for Inspecting a Defect - Google Patents

Abstract

The foreign material inspection apparatus according to the present invention includes an image sensing unit for acquiring an image image of the lens module by mounting the lens module; A diffusion plate positioned on the image sensing unit; An illuminator positioned on the diffuser plate; A first display connected to the image sensing unit and configured to display an image image obtained from the image sensing unit; An image post-processing unit coupled to the first display and configured to post-process the image using a histogram equalization method; And a second display connected to the image post-processing unit and displaying a post-processed image.

Foreign object, lens module, diffuser plate, image post-processing unit, dimming machine

Description

Apparatus and Method for Inspecting a Defect}

The present invention relates to a foreign material inspection apparatus and method, and more particularly to a foreign material inspection apparatus and method fixed to the camera or the image sensor module (ISM) lens surface.

In general, when a foreign material is fixed on the lens surface of the camera or an image sensor module (ISM), the amount of light flowing into a specific portion of the CCD sensor surface by the foreign material is reduced, thereby causing a blurring of the image. For this reason, defects due to foreign matters are detected by setting a size reference for the foreign material on the lens surface and assuming that the size of the foreign material is larger than the reference, which will cause spots on the image. However, in recent years, as the ISM becomes smaller and more than 3 megapixels, foreign matter smaller than the existing foreign matter standard may cause stains on the image, and thus, the foreign matter standard is required to be strengthened.

In the case of existing foreign material standards, the same foreign material standard is applied to each lens. However, each lens has a different relative distance from the image sensor, and the occurrence of image spots is directly affected by the size of the relative distance from the image sensor. Therefore, simply reinforcing the foreign material management standard of the lens surface to detect even the small size foreign material may cause overdetection of the foreign material which does not affect the actual image, which may lead to deterioration of product yield.

The most reasonable way to solve this problem is to find out the maximum size of the foreign material in each lens that does not cause image blur. However, the material of the actual foreign material is very diverse, even if the foreign material of the same size may have a different effect on the actual image due to the difference in the material. In addition, applying experiments by applying a certain size of a foreign material to a desired position of a specific lens is a difficult task and an unproductive method, considering the current short life cycle for each model.

The present invention obtains an image image of the lens module in a lens module state in which lenses are assembled to detect a defect caused by a foreign material, and detects a foreign material through an image post-processing image obtained by post-processing the image image. It is an object to provide an apparatus and method.

The foreign material inspection apparatus according to the present invention includes an image sensing unit for acquiring an image image of the lens module by mounting the lens module; A diffusion plate positioned on the image sensing unit; An illuminator positioned on the diffuser plate; A first display connected to the image sensing unit and configured to display an image image obtained from the image sensing unit; An image post-processing unit connected to the first display and configured to image-process the image image; And a second display connected to the image post-processing unit and displaying a post-processed image.

In the present invention, the diffusion plate may be a translucent acrylic plate.

In the present invention, the diffusion plate may have a thickness of 1 ~ 2.5 mm.

In the present invention, the illuminator may be a plurality of LEDs.

In the present invention, the illuminator may further comprise a dimming (dimming).

In the present invention, the image sensing unit comprises a module holder for mounting the lens module; And a sensor for obtaining an image image of the lens module.

In the present invention, the image post-processing unit may perform image post-processing using a histogram equalization method.

The foreign material inspection method according to the present invention comprises the steps of: driving an illuminator located on the diffuser plate to obtain an image image of the diffuser plate of the lens module from the image sensing unit; Post-processing the image by maximizing the difference in luminance of the image; Displaying the image post-processed image on the display; And detecting a foreign material by identifying an image post-processing image displayed on the display.

In the present invention, the image post-processing may be performed after the image using the histogram equalization method.

In the present invention, the post-processing of the image may include converting the image image obtained from the image sensing unit into a black and white image; And converting the converted black and white image into an image post-processing image using the histogram equalization method.

A method for manufacturing a lens module for an ISM comprising a resolution test process for an assembled lens module according to the present invention, the method comprising: obtaining an image image of a diffuser plate of a lens module from an image sensing unit; Post-processing the image by maximizing the difference in luminance of the image; Displaying the image post-processed image on the display; The foreign material inspection method may include performing a foreign material detection method by identifying an image post-processing image displayed on the display.

A method for manufacturing a lens module for an ISM comprising a final visual inspection process for an assembled lens module according to the present invention, the method comprising: obtaining an image image of a diffuser plate of a lens module from an image sensing unit; Post-processing the image by maximizing the difference in luminance of the image; Displaying the image post-processed image on the display; The foreign material inspection method including identifying the image post-processing image displayed on the display may be performed as a next step of the final appearance inspection process.

The foreign material inspection apparatus and method according to the present invention made as described above obtains an image image of the lens module in the state of the lens module assembled lenses, and detects the foreign matter through the image post-processing image obtained by post-processing the image image As a result, the foreign matter detection rate affecting the image can be greatly improved, and since the equipment for resolving power inspection is utilized without requiring a sophisticated optical system, there is a cost effective effect.

In addition, since foreign substances affecting the image are directly detected, there is no need for a foreign substance management criterion, thereby eliminating controversy about the foreign substance criteria.

Hereinafter, with reference to the embodiments of the present invention shown in the accompanying drawings will be described in detail the present invention. However, the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

1 is a block diagram of a foreign material inspection apparatus according to an embodiment of the present invention, Figure 2 is a schematic diagram showing a method of obtaining an image image for the diffuser plate of the lens module, Figure 3 (a) is using a histogram equalization method FIG. 3 (b) is a graph showing the luminance distribution of the post-processed image after the post-processing image using the histogram equalization method.

Referring to FIG. 1, a foreign material inspection apparatus according to an exemplary embodiment may include an image sensing unit, a diffusion plate, an illuminator, a first display, an image post-processing unit, and a second display.

The image sensing unit may include a module holder and a sensor. The module holder may serve to seat the lens module, and the sensor may serve to obtain an image image of the lens module seated on the module holder.

The diffuser plate may be a translucent acrylic plate located on the image sensing unit. In addition, the diffusion plate may have a thickness of 1 to 2.5 mm, and may serve to evenly spread the light passing through the lens module.

The illuminator is located on the diffuser plate and may be a plurality of LEDs, and the illuminator may further include a dimming device capable of adjusting the brightness of the LEDs. In addition, the illuminator may serve to provide a light source to the diffusion plate.

The first display may be connected to the image sensing unit and serve to display an image image of the diffusion plate of the lens module acquired by the image sensing unit.

The image post-processing unit may be connected to the first display and perform image post-processing to maximize the luminance difference by using histogram equalization method of the image image acquired by the image sensing unit to obtain an image post-processing image.

The second display may be connected to the image post-processing unit, and may display a post-processing image acquired by the image post-processing unit to identify foreign matters affecting the image.

A method of obtaining an image image of a diffusion plate of a lens module will be described in detail with reference to FIG. 2. First, a lens module is mounted on a module holder of an image sensing unit. A diffuser plate made of translucent plastic is installed on the upper side of the lens module, and the diffuser plate and the lens surface must be parallel to each other. In addition, the illuminator is installed above the diffuser plate to add insufficient light, and the illuminator should be installed to evenly illuminate the entire diffuser plate surface. As described above, after the image sensing unit, the diffusion plate, and the illuminator are installed, an image image of the diffusion plate of the lens module may be acquired by the sensor of the image sensing unit.

An image post-processing process will be described with reference to FIGS. 3A and 3B. First, when an image image obtained from the image sensing unit is input from the first display to the image post-processing unit, the image image is converted into a black and white image. Thereafter, the converted monochrome image is converted into an image post-processing image using a histogram equalization method and displayed on the second display.

In this case, the historam equalization method used in the process of converting the converted monochrome image into an image post-processing image will be described in more detail. In general, in the case of a black and white image, the luminance of the image is represented by a number of 0 to 255, and the luminance distribution of the image is distributed over a partial region as shown in FIG. In particular, the narrower the luminance distribution width of the image, the more difficult it is to grasp the image visually. The historam equalization method here maximizes the luminance difference of the image by expanding the luminance distribution width of the image to be uniformly distributed from 0 to 255 as shown in FIG. 3 (b), and makes it easier to visually identify the image. It becomes

Therefore, when the image image obtained from the lens module is converted by using the historam equalization method, the visibility of the foreign material is greatly increased, and thus, it is easier to determine whether the foreign material affecting the camera or the ISM lens surface.

In general, a method for manufacturing a lens module for an ISM includes: a) injecting and coating a lens, b) assembling the lens module using the injected and coated lens, c) inspecting the resolution of the assembled lens module, d A) inspecting the final appearance of the lens module that passed the resolution test, e) cleaning and packaging the lens module that passed the final appearance inspection, and f) shipping inspection of the cleaned and packaged lens module.

At this time, when the foreign material inspection method according to an embodiment of the present invention is performed after the resolution test step of the lens module manufacturing process for the ISM will be able to minimize the inspection time and inspection equipment required for the foreign material inspection.

In addition, the foreign material inspection method according to an embodiment of the present invention may be performed through the image image obtained during the final appearance inspection after the final appearance inspection step of the lens module manufacturing process for the ISM.

Figure 4 is a flow chart in the case of performing a foreign material inspection method in a resolution test after the process.

Referring to FIG. 4, first, a lens module is mounted on a module holder to perform a resolution test. If the lens module does not pass the resolution test, the defect is judged, and when the lens module passes the resolution test, the image image of the diffuser plate is taken from the sensor, and the image post-processing image is acquired. To determine whether there is any foreign matter affecting the image. At this time, if there is a foreign object affecting the image in the lens module, the defect is judged. If there is no foreign material affecting the image, a good quality judgment is made, and the lens module is removed from the module holder to terminate the inspection.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims, and various forms of substitution, modification, and within the scope not departing from the technical spirit of the present invention described in the claims. It will be apparent to those skilled in the art that changes are possible.

1 is a block diagram of a foreign material inspection apparatus according to an embodiment of the present invention.

2 is a schematic diagram illustrating a method of obtaining an image image of a diffuser plate of a lens module.

Fig. 3A is a graph showing the luminance distribution of an image image before post-processing using the histogram equalization method.

Fig. 3B is a graph showing the luminance distribution of the post-processed image after post-processing using the histogram equalization method.

Figure 4 is a flow chart in the case of performing a foreign material inspection method in a resolution test after the process.

Claims (16)

An image sensing unit which mounts the lens module to obtain an image image of the lens module; A diffusion plate positioned on the image sensing unit; An illuminator positioned on the diffuser plate; A first display connected to the image sensing unit and configured to display an image image obtained from the image sensing unit; An image post-processing unit coupled to the first display and configured to post-process the image using a histogram equalization method; And And a second display connected to the post-processing unit and displaying a post-processed image. The method of claim 1, The diffusion plate is a foreign material inspection device that is a translucent acrylic plate. The method according to claim 1 or 2, The diffusion plate is a foreign material inspection device having a thickness of 1 ~ 2.5 mm. The method of claim 1, The illuminator is a foreign material inspection device that is a plurality of LEDs. The method according to claim 1 or 4, The illuminator further includes a dimming device. The method of claim 1, The image sensing unit, A module holder for seating the lens module; And a sensor for obtaining an image image of the lens module. delete Driving an illuminator positioned on the diffuser plate to obtain an image image of the diffuser plate of the lens module from the image sensing unit; Post-processing the image by maximizing a luminance difference of the image by using a histogram equalization method; Displaying the image post-processed image on the display; And And detecting a foreign material by identifying the image post-processed image displayed on the display. delete The method of claim 8, The image post-processing step, Converting the image image obtained from the image sensing unit into a black and white image; And And converting the converted black and white image into an image post-processing image using histogram equalization method. In the lens module manufacturing method for an image sensor module (ISM) comprising a resolution inspection process for the assembled lens module, Obtaining an image image of the diffuser plate of the lens module from the image sensing unit; Post-processing the image by maximizing a luminance difference of the image by using a histogram equalization method; Displaying the image post-processed image on the display; And And detecting a foreign material by identifying an image post-processed image displayed on the display, wherein the foreign material inspection method is performed as a next step of the resolution test process. delete The method of claim 11, The image post-processing step, Converting the image image obtained from the image sensing unit into a black and white image; And And converting the converted black and white image into an image post-processing image using histogram equalization method. In the lens module manufacturing method for an image sensor module (ISM) comprising a final visual inspection process for the assembled lens module, Obtaining an image image of the diffuser plate of the lens module from the image sensing unit; Post-processing the image by maximizing a luminance difference of the image by using a histogram equalization method; Displaying the image post-processed image on the display; And And detecting a foreign material by identifying the image post-processed image displayed on the display. The method of manufacturing a lens module for an ISM (Image Sensor Module), wherein the foreign material inspection method is performed as a next step of the final appearance inspection process. delete The method of claim 14, The image post-processing step, Converting the image image obtained from the image sensing unit into a black and white image; And And converting the converted black and white image into an image post-processing image using histogram equalization method.

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