17. Creation of Light Anatomy of a Die P layer P/N Junction N layer Substrate P Electrode (Anode) N Electrode (Cathode) “ Active Layer” “ Depletion Layer” “ Forbidden Layer” Junction
18. Creation of Light Anatomy of a Die P/N Junction Substrate (Anode) (Cathode) Current + + + + + + + + + + + + + + + Current Out - - - - - - - - - - - - - - - - - - - - - - - - - - - - Bond Wire Applying current causes electrons to flow, the union creates a release of energy - either light or heat
20. Spectral Power Distribution Comparison Typical White Power LED (blue diode w/phosphors) Spike at 450 nm represents the contribution from the blue diode. Wavelengths of light above 500 nm are result of the phosphors.
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22. InGaN Blue LED- Creating White Light Indium Gallium Nitride (most common method for white)
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25. Results of Premium binning procedures Due to variance during production, a bin is a “zone” of chromaticity in which a customer will receive product. in variance Red bin represents a 57% reduction
26. Standards for LED product testing L70 “ End of Life” determined at 70% of initial lumen output. Junction Temperature, Operating Temperature, Drive Current all play a role in the determination of L70
27. Standards for LED product testing L70 predicated on keeping the LEDs cool.
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30. IES LM-80-2008 Approved Method for Measuring Lumen Depreciation of LED Light Sources “ Specifies a standard method for measuring the lumen depreciation of LEDs, allowing calculation of LED lifetime.” This is the actual, real-life (lab) lumen/life testing of diodes (but not in a luminaire). 6,000 hours are required, however 10,000 hours are preferred. This equates to 8 months of operational testing! Prior to LM80, most reputable LED manufacturers used the Assist method of calculation, proven to be very reliable. Standards for LED product testing ___________________________________________________
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35. Myth #4 LEDs are inexpensive No, they are more expensive – but they are starting to come down.
49. The 12 questions… 2) Has your diode supplier provided an IESNA LM-80 Test? LM-80 was finalized and published by the IESNA in September of 2008. All reputable LED manufacturers should now be submitting existing and new LED packages for LM-80 testing. If your fixture manufacturer cannot produce LM-80 test results for the LED they are employing in their luminaire – buyer beware!
50. The 12 questions… 3) What is the operating range specification and what is the maximum junction temperature (Tj) of the lamps over that percentage range? Each LED has operating characteristics that need to be adhered to when employing them in a lighting fixture. The most critical item of note is the LED package operating junction temperature or Tj. The Luminaire manufacturer should be able to provide not only maximum rated junction temperature for the LED, but also what the Tj is as operated in their fixture. Care should be taken when applying luminaires in different climates (operating temperatures). Quality Luminaire manufacturers will build in an allowance in their design for variances in ambient operating temperatures.
51. The 12 questions… 4) What is the expected L-70 lifetime of your fixture ? How was it calculated? L70 is a designation for the amount of time it will take a LED to depreciate to 70% initial lumen output (as set forth by LM-79 photometric testing) in a fixture. Again, what is the fixture’s L70 and at what ambient is that tested at? Is it a realistic ambient?
52. The 12 questions… 5) Can you supply an IESNA LM-79 test report and is it from a third party laboratory with an .ies file? Independent Testing Laboratories, Boulder Colorado is one of the premier testing houses for lighting fixtures.
53. The 12 questions… 6) What are the delivered lumens and LPW of the fixture? The delivered lumens stated in fixture manufacturer’s literature should reflect the “total” lumens each fixture produces. When evaluating the specification sheet, the stated luminous output is the same as the output reported to us in our LM-79 test, in other words, “no in-house tricks.” We do not report “ lighthead” lumens, but actual light delivered out of the fixture. Fixture wattage should be total draw, including driver losses.
54. The 12 questions… 7) Is the chromaticity of the fixture in the ANSI C78.377A color space and is it stable over time? How do you know? Reputable LED manufacturers all publish binning practices. Typical bins are representative of (7) MacAdams Ellipse. Lighting Class LEDs should be much more precise (3) Ellipse.
55. The 12 questions… MacAdams Ellipse Over 90 percent of the population can see the difference in (7) Ellipse A reduction from 7 to 3 MacAdams Ellipse reduces the percentage to less than 65 percent.
56. The 12 questions… 8) Does the color of the light output vary from fixture to fixture or in different spatial locations for a single fixture? Fixture manufacturers need to be very careful and record keep the bins from which they receive their LED and supply to project sites. How critical this is depends on the quantity of LEDs used in the fixture design, as well as the size of the bins in which they purchase from.
57. The 12 questions… 9) What is the power factor of your fixture? How much power does it consume in the off position? Properly designed luminaires should consume no power in the off position. Power factor is how effectively the electrical design (driver) uses the input power it receives. Luminaires should meet or exceed the USDOE Energy Star rating.
58. The 12 questions… 10) Have you applied for DOE Energy Star for this fixture? Why/Why not? Energy Star has traditionally been associated with residential grade products. Although it is better to have than have not, many new luminaires have either not been submitted or await the review of the DOE. Similar to appliances, Energy Star sets a minimum performance level and is not the end all to quality LED luminaires.
59. The 12 questions… 11) Is your fixture lead free, mercury free, and RoHS compliant? In order to meet the Reduction of Hazardous Substances compliance, lead and mercury are eliminated from the product, as well as an extensive list of other potentially harmful materials.
60. The 12 questions… 12) What is the warranty and do you have the means to STAND BEHIND IT? LED Lighting represents an unprecedented level of reliability and the manufacturer should have the confidence to stand behind their design. Warranties should be a minimum of 3 year, as long as 5 year and incorporate not only the LED circuitry, but driver and optics as well. Does the manufacturer you are dealing with have experience in the lighting industry? Have they stood behind prior technologies? Will they be around in the future to service an offered warranty?
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