CN106526917A - Liquid crystal screen dot matrix detection device achieving scanning by means of line-scan digital camera - Google Patents

Abstract

The invention relates to a liquid crystal screen dot-matrix detection device scanned by a line-scan camera, which belongs to the technical field of liquid crystal screen defect detection. In a dark room environment without ambient light, place the LCD screen on the LCD backlight panel of the same size as the LCD screen at zero distance, so that the LCD screen and the backlight panel are completely overlapped; the lens is installed on the line array camera, and the camera is fixed on the mobile camera through bolt connection. The linear array imaging system is formed on the mechanism, and the linear array imaging system is located directly in front of one side of the LCD screen; the LCD backlight and the LCD screen are lit, and the moving mechanism is adjusted so that the lens direction of the linear array imaging system is perpendicular to the plane where the LCD screen is located. This enables the line array imaging system to collect all the pixels in the vertical direction facing the liquid crystal screen. Utilizing the characteristics of fast image acquisition speed of the line array camera, the detection speed is greatly improved. Compared with the general defect detection image processing algorithm, it has higher efficiency and better reliability.

Description

A liquid crystal screen dot-matrix detection device scanned by a line-scan camera

technical field

The invention relates to a liquid crystal screen dot matrix detection device scanned by a line array camera, which belongs to the technical field of liquid crystal screen defect detection.

Background technique

LCD screens are usually precision-processed and manufactured in a dust-free workshop, but it is still inevitable that there will be various defects, such as dead pixels, bright spots, dark spots, foreign matter stains, and so on. The traditional detection method of liquid crystal screen defects uses artificial vision. This method is affected by human subjective judgment, which may lead to false detection and missed detection. In addition, the detection speed is relatively slow.

Using machine vision to detect LCD screen defects is more ideal and more accurate, so using machine vision to detect LCD screen defects will become the mainstream. When machine vision is used to detect defects in LCD screens, the front-facing camera is generally used for image acquisition, and there are the following difficulties: First, due to the relatively high pixels of the LCD screen and the large overall size of the screen, it is difficult for the front-facing camera to accurately collect images on the screen of every pixel. Second, affected by the brightness of the liquid crystal screen during detection, a long exposure time is required when collecting information, and the detection speed is relatively slow. The third is that due to the limitations of the general camera itself in the visual system, the information of the edge part of the collected picture is not accurate enough. Fourth, even if the entire LCD screen can be captured by a general camera, its defect detection algorithm is very complicated.

The defect detection device of the line array camera scanning liquid crystal screen invented by this project has solved the above-mentioned problems in the detection using the front view camera well.

Contents of the invention

The invention is a dot-matrix quality detection device of a liquid crystal screen scanned by a line-scan camera, which can quickly and efficiently detect various defects of the liquid crystal screen.

The specific equipment of the device of the present invention includes a computer, a liquid crystal backlight board, a liquid crystal screen, a lens, a line-scan camera, a moving mechanism, and an external trigger module.

The specific embodiment of the device of the present invention is: in a darkroom environment without ambient light, the liquid crystal screen is fixedly placed on the liquid crystal backlight board of the same size as the liquid crystal screen, so that the liquid crystal screen and the backlight board are completely overlapped; the lens is installed in a line array camera First, the camera is fixed on the moving mechanism by bolts to form a line array imaging system, and the line array imaging system is located directly in front of one side of the LCD screen; the LCD backlight and the LCD screen are lit, and the moving mechanism is adjusted so that the line array imaging system The direction of the lens is perpendicular to the plane where the LCD screen is located, so that the line array imaging system can collect all the pixels in the vertical direction facing the LCD screen; the computer and the external trigger module are connected by data lines, and the computer and the line array imaging system pass through Network cable and data cable connection.

The line array imaging system starts to capture images, and the moving distance of the control mechanism is the imaging width of the line array camera. The external trigger module controls the camera to capture images. The line array camera captures an image once the mechanism moves until all the pixels of the LCD screen are captured. Collected. The line array imaging system inputs the collected images to the computer for processing. The external trigger circuit can generate a pulse signal, the pulse width controls the exposure time of the camera, and adopts a variety of periodic pulse widths for image acquisition, which can obtain images under multiple exposure conditions at one time, and then achieve large dynamic range imaging through image synthesis.

The positive effects of the present invention are:

1. When using a line-scan camera to detect LCD screen defects, the resolution of the line-scan camera is more than twice the resolution of the LCD screen, and each pixel of the LCD screen can be accurately detected.

2. Using the fast image acquisition speed of the line array camera, the detection speed is greatly improved.

3. After the visual inspection device adopts the linear scanning method to form images, the images have good suppression in the scanning direction. After the images are superimposed by the computer, a standard image template can be generated, and the template is compared with the actual image of each line. Whether the LCD screen is defective can be judged by simple calculation, which is more efficient and reliable than the general defect detection image processing algorithm.

4. The camera used in the above-mentioned device is a line-scan camera, because the high sensitivity of the line-scan camera overcomes the blurred image collected by general cameras.

5. The self-developed LCD screen image detection algorithm is highly targeted and efficient. The basic idea of the image processing algorithm is geometric correction (RGB splitting, boundary calculation, boundary line fitting, corner calculation, affine transformation), pixel segmentation (area segmentation), obtaining pixel information, and standard LCD screen compare information and draw conclusions.

Description of drawings

Fig. 1 is a structural diagram of the present invention.

detailed description

As shown in FIG. 1 , a dot-matrix quality inspection device of a liquid crystal screen that scans with a line-scan camera can quickly and efficiently detect various defects of the liquid crystal screen.

The specific equipment of the device of the present invention includes a computer, a liquid crystal backlight board, a liquid crystal screen, a lens, a line-scan camera, a moving mechanism, and an external trigger module.

The specific embodiment of the device of the present invention is: in a darkroom environment without ambient light, the liquid crystal screen is fixedly placed on the liquid crystal backlight board of the same size as the liquid crystal screen, so that the liquid crystal screen and the backlight board are completely overlapped; the lens is installed in a line array camera First, the camera is fixed on the moving mechanism by bolts to form a line array imaging system, and the line array imaging system is located directly in front of one side of the LCD screen; the LCD backlight and the LCD screen are lit, and the moving mechanism is adjusted so that the line array imaging system The direction of the lens is perpendicular to the plane where the LCD screen is located, so that the line array imaging system can collect all the pixels in the vertical direction facing the LCD screen; the computer and the external trigger module are connected by data lines, and the computer and the line array imaging system pass through Network cable and data cable connection.

The line array imaging system starts to capture images, and the moving distance of the control mechanism is the imaging width of the line array camera. The external trigger module controls the camera to capture images. The line array camera captures an image once the mechanism moves until all the pixels of the LCD screen are captured. Collected. The line array imaging system inputs the collected images to the computer for processing.

The linear array imaging system in the device is fixed, and the moving mechanism carries the liquid crystal screen and the liquid crystal backlight plate to perform translational movement relative to the linear array imaging system.

The external trigger circuit can generate a pulse signal, and the pulse width controls the exposure time of the camera, and adopts a variety of periodic pulse widths for image acquisition, which can obtain images under multiple exposure conditions at one time, and then achieve large dynamic range imaging through image synthesis.

The resolution of the line scan camera is more than twice the resolution of the LCD screen, so as to collect the information of each pixel of the LCD screen.

The linear array imaging system in the device transmits the collected images to the computer, which is characterized in that the transmittance of the independent pixels of the LCD screen is obtained through the image processing algorithm on the computer, and the basic idea of the image processing algorithm is geometric correction (RGB demolition points, boundary calculation, boundary line fitting, corner calculation, affine transformation), pixel segmentation (area segmentation), calculation of pixel information, comparison with standard LCD screen information, and conclusions.

Under the premise of ensuring that every pixel of the LCD screen can be collected, it can be a monochrome black and white camera, or a color camera.

The camera in the current imaging system of the above-mentioned devices is a line scan camera or a TDI camera, and a TDI (Time Delay Integration) camera is equivalent to a multi-row line scan camera. sensitivity and dynamic range.

Claims (7)

1. A liquid crystal screen dot matrix detection device that adopts a line array camera to scan, is characterized in that: the device includes a computer, a liquid crystal backlight, a liquid crystal screen, a camera lens, a line array camera, a moving mechanism, and an external trigger module; In a darkroom environment without ambient light, place the LCD screen on the LCD backlight panel of the same size as the LCD screen at zero distance, so that the LCD screen and the backlight panel are completely overlapped; the lens is installed on the line array camera, and the camera is fixed on the mobile camera through bolt connection. A linear array imaging system is formed on the mechanism, and the linear array imaging system is directly in front of one side of the LCD screen; the LCD backlight and the LCD screen are lit, and the moving mechanism is adjusted so that the lens direction of the linear array imaging system is perpendicular to the plane where the LCD screen is located. The linear array imaging system can collect all the pixels in the vertical direction facing the LCD screen; the computer and the external trigger module are connected by data lines, and the computer and the line array imaging system are connected by network cables and data lines; The line array imaging system starts to capture images, and the moving distance of the control mechanism is the imaging width of the line array camera. The external trigger module controls the camera to capture images. The line array camera captures an image once the mechanism moves until all the pixels of the LCD screen are captured. After the collection is completed; the line array imaging system will input the collected images to the computer for processing. 2. A liquid crystal dot-matrix detection device scanned by a line-scan camera according to claim 1, characterized in that: the line-scan imaging system in the device is fixed, and the moving mechanism carries the liquid crystal screen and the liquid crystal backlight Make translation relative to the linear array imaging system. 3. A liquid crystal dot matrix detection device scanned by a line array camera according to claim 1, characterized in that: the external trigger circuit generates a pulse signal, the pulse width controls the camera exposure time, and adopts a variety of periodic changes. The pulse width is used for image acquisition, and images under multiple exposure conditions are obtained at one time, and then images with a large dynamic range are realized through image synthesis. 4. A kind of liquid crystal screen dot matrix detection device that adopts line array camera scanning according to claim 1, is characterized in that: the resolution of line array camera is greater than more than 2 times of the liquid crystal screen resolution, to collect the liquid crystal screen information about each pixel. 5. A kind of liquid crystal screen dot matrix detection device that adopts line array camera scanning according to claim 1, it is characterized in that: the line array imaging system in the device transmits the collected image to the computer, it is characterized in that on the computer through The image processing algorithm obtains the transmittance of individual pixels of the LCD screen. The basic ideas of the image processing algorithm are geometric correction, pixel segmentation, obtaining pixel information, comparing with the information of the standard LCD screen, and drawing conclusions. 6. A liquid crystal screen dot matrix detection device that uses a line array camera to scan according to claim 1, characterized in that: it is a monochrome black and white camera or a color camera under the premise of ensuring that each pixel of the liquid crystal screen can be collected camera. 7. A liquid crystal screen dot-matrix inspection device scanned by a line-scan camera according to claim 1, wherein the camera in the imaging system is a line-scan camera or a TDI camera.