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Thread: No more blue light emitted from LED's is coming ......................

  1. #1
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    Redhot Jumper No more blue light emitted from LED's is coming ......................

    THE OPTICAL SOCIETY (OSA)International Year of Light 2015

    A New Design for an Easily Fabricated,
    Flexible
    and Wearable White-Light LED


    By Taking Advantage of Novel Design Patterns, Researchers in Taiwan have Developed a Highly Flexible White Light LED that uses Cheap, Readily-accessible Components

    WASHINGTON — Researchers from National Chiao Tung University, Taiwan have created highly flexible, efficient white LEDs with potential use in wearable displays and non-flat surfaces, such as curved and flexible television screens. While the design itself is new, the LED was completely fabricated from pre-existing technologies, allowing others to easily replicate and build on the platform.

    "Compared to organic light-emitting diodes, this design of flexible LEDs can be very attractive, due to the low cost, prolonged lifetime and high efficiency. In addition, all of the technologies associated with this design are currently available," said Chien-Chung Lin, associate professor, College of Photonics, National Chiao Tung University, Taiwan.

    A paper by Lin, Professor Hao-Chung Kuo, and their research team appears this week in Optics Express, a journal published by The Optical Society (OSA). This is their first flexible LED device, while their previous work had involved conventional gallium-nitride LEDs.

    The researchers’ off-the-shelf LED device gets its flexibility from its two primary materials, polyimide and polydimethylsiloxane. To construct it, Lin and his colleagues first covered a polyimide substrate with copper foil shielding tape. In a process known as flip-chip bonding, which reduces thermal resistance and results in higher heat dissipation than traditional wire bonding, they mounted 81 Blue LED chips, measuring 1.125 mm x 1.125 mm, to the foil in an upside down position.

    To provide a warm white-yellow light, the researchers then added another layer consisting of a yellow phosphor film that had been mixed and spin-coated in polydimethylsiloxane, or PDMS, a widely used silicone-based organic polymer. It was chosen for its high degree of transparency, stability, and flexibility. The final film measured five centimeters by five centimeters, but there is no reasonable limitation to the size of the film.

    The researchers ran the device for a standard 1,000 hours, to test its durability, finding that its emission decayed by only 5%. Its potential for use in wearables was demonstrated when subjected to bending tests. It held its power output when bent to a curvature with a 1.5-cm radius. It also exhibited a light efficiency of 120 lumens per watt.

    source: ============>
    http://www.osa.org/en-us/about_osa/n...d,_flexible_an
    Last edited by Chris Ryser; 09-06-2015 at 02:11 PM.

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    Redhot Jumper blue light reflection by AR coatings will be ancient in no time,

    The newest invention of partial blue light reflection by AR coatings will be ancient in no time, as every LED manufacrturer will run to get the new white ones. Cheap and easy to make.

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    You had my hopes up, but they were dashed by reading that article carefully. Their new LEDs are BLUE emitters, to which they add Yellow LEDs for the warm natural look. However, the blue wavelengths will still be in there, strong as ever, as far as I can tell.

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    Blue Jumper blue light has been neutralized and eliminated, it is not there anymore

    We are talking about that visible blue light has been neutralized and eliminated, it is not there anymore. I developed the first one step 100% blue blocker dye for CR 39 in 1984. They are just doing a similar coating to the lens that absorbs the blue light.

    The filter is most probably better than your AR coating reflecting it.





    Last edited by Chris Ryser; 09-08-2015 at 03:53 AM.

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    Quote Originally Posted by Chris Ryser View Post
    We are talking about that visible blue light has been neutralized and eliminated, it is not there anymore.

    The filter is most probably better than your AR coating reflecting it.
    As I understand physics, the blue is not "neutralized" or "eliiminated" at least not by the emitters as described above. It's all ADDITIVE. Remember, white light is made up of all three primary wavelenghts. You cannot have white without blue in the mix.

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