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Company News >> Application of Imaging Chromaticity Luminance Meter in LCD Screen Inspection 29th, Dec,2016
                 Abstract: mura refers to the display brightness is not uniform, causing a variety of signs of the phenomenon. The simplest way to judge is to switch to a dark screen in the dark room, and other low-gray screen and then from a variety of different angles to see, with a wide range of process flaws, there are various types of LCD display May be horizontal stripes or forty-five degree angle stripes, may be cut very straight box, may be a corner of a piece, may be no rules of flowers at all, the East piece of a piece of West tracesMura test solution.

1. Liquid crystal defects
1) Zara-light leakage, light leakage is not closely aligned with the LCD screen with the frame lead to direct transmission of light out of the tube. 2) Zure - misalignment, refers to the LCD screen filter unit and the TFT bit error caused by defects 3)SIMI-substrate stains 4) Mura- is the display brightness caused by uneven trace of the phenomenon, the most Simple method of judgment is to switch to a black screen in the dark room and other low-gray screen, and then from a variety of different angles to see hard, with a wide range of process flaws, LCD monitors have a wide range of mura . Above all kinds of defects, Mura is   the most difficult to detect, because it is optical, colorimetric and human psychology of a combination.
2. Mura definition
Mura was originally a Japanese word, with the Japanese LCD monitor to flourish around the world, the word in the display industry has become a world can pass text. Mura refers to the display brightness is not uniform, causing a variety of signs of the phenomenon. The simplest way to judge is to switch to a dark screen in the dark room, and other low-gray screen and then from a variety of different angles to see, with a wide range of process flaws, there are various types of LCD display May be horizontal stripes or 45 degrees angle stripes, may be cut very straight box, may be a corner of a piece, may be no rules of flowers at all, the East West a piece of traces. "Liquid crystal display devices Part 2-2-4: Detailed specifications for color matrix liquid crystal display modules for mobile phones" states that the Mura should not be visible after the 6% neutral density filter is covered, or against the standard sample. However, most of the quality of LCD panel is determined by professional training personnel to the human eye detection, implied human visual constraints, training and subjective identification and other factors, prone to unreliable judgments, as between producers and consumers Dispute, so manufacturers  actively develop the machine vision detection architecture.
3. Mura Testing and Quantification SEMI sets a standard for Mura testing.
• Cjnd is the minimum perceivable contrast difference for the mura defect. • Sjnd is the mura defect area under Cjnd. Obviously, each Sjnd  has a fixed Cjnd counterpart. Sjnd and Cjnd are decreasing relations, the larger the area, the lower the contrast of the human eye is more sensitive to the mura. Three points on the map can explain the relationship between Sjnd and Cjnd, the arrow points to the same two-point gray, but the area is not the same, causing different visual sensitivities. WP640 / 690 products because of a high degree of sensitivity, can distinguish Mura's fine gray difference. The image below shows some of the mura images that have been calculated: Thanks to the highly accurate chroma brightness test, Westboro Photonics' WP640 / 690 accurately tests and quantifies the mura's position for Mura's automated  testing and Analyse. The WP640 / 690 series has a 4 megapixel / 9 megapixel Burr cooling high-sensitivity CCD with a dynamic range of over 100,000: 1 and is a prerequisite for testing mura. The WP640 and WP690 imaging brightness meters come with Photometrica software to provide users with the most productive software environment, whether it is simple or in-depth analysis. Using the optional script or the Software Development Kit (SDK), all of the software's results and analysis capabilities can be efficiently automated.

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