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TLC 128A – ACTUALLY SEEING “Effective Projected Luminous Lens Area” (EPLLA)

Effective Projected Luminous Lens Area (EPLLA) is the portion of the faceted projecting areas of Brake/Turn Signal Lights that you actually can see specifically directed light emanating from when viewed anywhere within the 20° Left to 20° Right; 10° Up to 10° Down “Test Pattern”.

When you can look at any Lit Brake or Turn Signal Light at any angle within the Optical FVMSS #108 “Test Pattern” of 20° Left to 20° Right; 10°Up to 10° Down* and you can total all (and only) the Light emanating areas that are … by design … deliberately channeling light to your eyes within the “Test Pattern” giving a qualified total of 11-5/8 in² or more, you have an “EPLLA Compliant” Brake and Turn Light.

When looking “straight in” on a Brake/Turn Test Lamp with your head located ≈ 10 feet “straight out” from the center of the Light being Tested … the Areas that you initially see “light up” can officially be added to the “EPLLA Area Tally”, plus you can also add in all the areas that you see distinctly light up during the lateral and up and down movements of your head – anywhere within a rectangular scope of ≈ 10 inches to Left, ≈ 10 inches to Right, ≈ 5 inches Up*, ≈ 5 inches Down, where the 10 and 5 inch head movement borders represent the 20° Left – 20° Right, 10° Up – 10° Down official “Test Pattern” mandated for Photometric and EPLLA measurements by FMVSS #108.

If … in the case of the Optronics® example (attached) … all you see light up during the entire Test Pattern observations is only fourteen, 3/4” diameter Fresnel sets of Rings … the maximum “EPLLA Tally” is 14 X ∏ X (R²) or 14 X 3.14 X (3/8)² = 6.19 in².  Therefore, to get to the mandated 11-5/8in² … Optronics must provide 11-5/8 divided by 6.19 of these 3/4” diameter sets of Fresnel Rings, which means they need at least a total of ≈25 … therefore, at least another 11 must be added, thereby nearly doubling the cost for this Optronics® LED array in order for this light to be Legal.

If you’ll take the time to look straight in … 10 feet away … on any of the very “Cool Looking” … new car, “See Thru/Chrome” Incandescent Tail Light Assembly Designs … you’ll see some faceted areas light up when you’re looking straight in.  Then, as you move your head within the Test Pattern … you’ll see adjoining … yet different … facet areas light up while the initial areas “shut down”.   All the Areas that light up during the entire Test Pattern Observations can be Tallied for EPLLA Compliancebut no more! 

Small unlit areas between officially lit areas tallied during this Test are also addable to the EPLLA Tally as long as they’re not bigger than about 1/8” in width, which NHTSA and SAE has historically* allowed.  However, only ≈ 1/8” areas “between” seeably Lit areas can be tallied, whereas all transparent and all unlit areas between (in this case) the fourteen 3/4” Fresnel Ring Sets and the outer rim of the cover lens do not qualify for EPLLA tallying.  Just because an outer lens is 11-5/8 in² in area does not mean the Brake Light has a legal 11-5/8 in² of EPLLA.            *”Grandfathered In” allowance

Since Auto and SUV Tail Light Assemblies are usually quite “massive” compared to FMVSS #108 minimal size requirements … and probably average ≈ $100 each for their direct cost … Auto Designers have a lot of financial backing and extra area so they can easily meet the 7-3/4in² “EPLLA” (under 80”) mandate and this gives them the necessary financing and area to design a massive, intriguing, and attractive design all at the same time.  However, making a decent quality, lasting and economical ($5 to $10) 3 or 6/7 Function OEM Trailer, RV or Big Rig Tail Light Assembly that has a bona fide 11-5/8in² of EPLLA is a real economical and engineering challenge when dealing with an Incandescent Design and it is an impossible task when using just a few “inexpensive” Taiwan LEDs

*These popular “See Thru” Tail Light designs are proving to be very instrumental in selling expensive Cars, SUVs and Trucks!  See Thru's are “intriguing and attractive” to the Public and can greatly influence a $30,000 to $50,000 purchase just as our “See Thru/Chrome” designs can increase Trailer, RV and Truck sales as well.

The Federal “Effective Projected Luminous Lens Area” mandates that exist in FMVSS #108 for Brake/Turn and Lane Changing Lights that will assure the public adequate Lit areas of projected light can’t be accomplished using a few inexpensive LEDs.

Adequate “Effective Projected Luminous Lens Area” for Brake, Turn and Lane Changing Signals assures the public adequate conspicuity in up-close conditions when rain or snow (or dust) refracts light coming from plentiful numbers of “Effective Projected Luminous Lens Area Facetsso that drivers … following and to the side … are most apt to see and react to this large, bright, and spread out, area of properly projected light coming from one Incandescent or many LED Illuminating Sources.

Imagine if there was no “EPLLA” Requirementsand a single, small powerful one in² “Dot” of LED Light officially qualifies Photometrically for FMVSS #108 Brake/Turn Compliancy.  Human Testing has proven this limited EPLLA kind of design is not adequately effective when it comes to “conscious” and “subconscious stimulation” *, and additionally could, on occasion, be totally covered by mud or snow*.  Further, we know that a small single, high intensity Dot also produces unwanted glare and confusion, not to mention, providing a “styling no-no” that would never be considered by any Auto, SUV or Pick-Up Truck Designer.        *Human Tests substantiated

The minimal safety mandates for Effective Projected Luminous Lens Areas are spelled out in Federal Law! and violating these Laws may not get you into immediate trouble with Federal or State authorities, but ignoring these Laws will eventually cost you one way or another … in Recalls … in unhappy customers … and in damage, injury, or death Liability Lawsuits … that, I’m sure, everyone would just as soon avoid.

Sierra Design Mfg. Inc.        1113 Greenville Road         Livermore, CA  94550         Tel (925) 443-3140               


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