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Liquid Crystal Displays
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
The display row and column IC drivers are attached to the row and column bond pads of the display either by tape-automated bonding (TAB) using an ACA (anisotropic conductive adhesive), or chip on glass (COG) approaches. For backlighting transmissive LCDs, a fluorescent lamp is generally used. The R, G, B emission spectrum of the backlight and transmission spectrum of the R, G, B color filters are tuned together to achieve the desired color coordinates for the primary colors. Also, a diffuser is used to achieve uniform backlighting of the display. The backlight system may also use brightness enhancement films to tailor the light intensity distribution in the viewing cone. In addition to the earlier components, LCDs for specialized applications requiring enhanced performance may use a cover glass with EMI and antireflection coatings at the front, and a heater glass at the back side (between the backlight and the LCD) that facilitates low-temperature operation.
Automatic Visual Inspection
Published in K. S. Fu, Pattern Recognition, 2019
The most widely used illumination method is backlighting or silhouette.2,3,36,37 There are many industrial objects that can be represented adequately by outline. The silhouette produces a high-contrast image that can be easily thresholded to replace a binary image. A typical arrangement is shown in Figure 2. The outline of such silhouettes can be quite accurately defined. With well-collimated light, edge definitions of 10μm can be readily achieved. A large number of industrial measurement tasks can be met with this simple approach.
Comparative study of the ideal and actual adhesion interfaces of the die bonding structure using conductive adhesives
Published in The Journal of Adhesion, 2022
Naoaki Tsurumi, Yuta Tsuji, Taiki Baba, Hiroyuki Murata, Noriyuki Masago, Kazunari Yoshizawa
Light emitting diodes (LEDs) are one of the greatest inventions in microelectronics. Recently, LEDs have found various applications, such as solid-state lighting,[1] backlighting for liquid crystal displays (LCDs),[2] and headlamps for automatic vehicles[3,4] among other things. For high-power applications, a robust design applicable to thermal management is important for realizing reliable equipment. The reliability of LEDs has been well described in the literature.[5] There have been many efforts to improve the efficiency and lifetime of LED devices,[6–8] and the die attach quality is a key factor for this purpose because small voids or delamination may lead to an elevated temperature easily.[9] Delamination is one of the most serious failure modes. When the delamination occurs in a thermal path, the thermal resistance of the delamination layer is increased. The increased thermal resistance leads to an increased junction temperature, which also affects many other failure mechanisms and ultimately reduces the lifetime of LED packages.[5]
Inexpensive multispectral imaging device
Published in Instrumentation Science & Technology, 2022
In machine vision applications, there are common techniques for illuminating the measurand. Mostly, direct front illumination, bright-field illumination, dark-field illumination, or backlighting methods are preferred. In this study, the dark-field illumination and front-light illumination techniques are chosen. White light-emitting diodes (LEDs) are placed in cross layout to two sides of the measurement table, and a light source is placed on the top with a 25 cm working distance. In the experiments, an adjustable power source is used to power white LEDs to project the measurand.