Project Lighting

Design Considerations when Backlighting with LEDs

By Francis Nguyen, Osram Opto Semiconductors, Santa Clara, CA http://www.osram-os.com

Understanding LED thermal and electrical properties is key to making good design decisions for any LCD backlight application…

http://www.nxtbook.com/nxtbooks/hearst/projectlighting_201002/index.php?startid=5

Circuit Protection for LCD-TV Backlighting, Supplies

By Matt Williams Tyco Electronics’ Raychem Circuit Protection, Menlo Park, CA http://www.raychem.tycoelectronics.com

Good grounding practices, coupled with robust circuit protection devices, can enhance transient protection…

http://www.nxtbook.com/nxtbooks/hearst/projectlighting_201002/index.php?startid=10

Choosing lighting for machine-vision inspection

By Brent Evanger,Banner Engineering, Minneapolis, MN http://www.bannerengineering.com

Careful selection of dedicated lighting based on a few key factors can improve repeatability, reliability, and accuracy…

http://www.nxtbook.com/nxtbooks/hearst/projectlighting_201002/index.php?startid=15

Fig.1 Dedicated lighting offers numerous techniques and configurations able to meet diverse application requirements, such as those fro PCB inspection.

Welcome to another edition of Project Lighting

This winter’s issue looks at one of the hottest trends in lighting applications: the use of LEDs for image capture and display. In the first article in this issue,“Design considerations when backlighting with LEDs,” Francis Nguyen of Osram Opto Semiconductors explores the impact of LED thermal and electrical properties on LCD backlight design. He points out that, for their products to be successful, designers have to balance a number of considerations — display brightness, power consumption, parts count, battery life, physical size, and expected product lifetime — against the display’s intended use.

In the second article, “Circuit protection for LCDTV backlighting, supplies,” by Matt Williams of Tyco Electronics’ Raychem Circuit Protection, we learn about the new protection requirements imposed by LED backlighting. Williams notes that LEDs require precise power-management systems, since power-line-coupled transients and surges can reduce LED lifespan, and many LED drivers are susceptible to damage resulting from improper dc voltage levels and polarity. Further, LED-driver outputs can be damaged or destroyed by short circuits. While most LED drivers for LCD-TV applications have built-in safety features, including thermal shutdown and open/short detection, additional overcurrent protection devices may be needed to help protect ICs and other sensitive components.

The third article looks at imaging from the capture, rather than the display, vantage point. In “Choosing lighting for machine-vision inspection,” Brent Evanger of Banner Engineering shows how careful selection of dedicated lighting—based on a few key factors—can improve repeatability, reliability, and accuracy. He notes that engineers employing machine vision for quality control sometimes overlook the role proper lighting plays in obtaining accurate results. To select this lighting, engineers need to start by considering the target object/feature of interest in their inspection application, as well as the plant environment and the mounting requirements.

We hope you find these articles of interest, and we’d like to hear from you. If you’d like to give your opinion of them, or suggest future articles, please go to join the Project Lighting LinkedIn group at http://www.linkedin.com/groups?gid=98190.

Richard Comerford

For more information on Project Lighting, please visit http://electronicproducts-com-develop.go-vip.net/projectlighting