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Interpretation ID: LEDlamp.1

    Mr. Takayuki Amma
    Manager, Regulation & Certification
    Koito Manufacturing Co. , Ltd.
    4-8-3, Takanawa
    Minato-kuTokyo
    Japan


    Dear Mr. Amma:

    This responds to your letter, in which you seek clarification as to whether your proposed headlighting system would meet the requirements for a "combination headlighting system" under Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, Reflective Devices, and Associated Equipment. Specifically, your letter explained that you wish to combine an "integral beam lower beam headlamp" that uses LEDs (wired in series), with a "replaceable bulb upper beam headlamp". As discussed below, we believe that your proposed design with an LED array would be permissible, provided that it meets the applicable photometric requirements of the standard.

    As an initial matter, we note that your letter was in the first instance submitted under a request for confidentiality, but the agency denied that request in a separate letter dated June 20, 2005. In a July 13, 2005 e-mail to Eric Stas, you stated that you would not be appealing that determination.

    By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue FMVSSs that set performance requirements for new motor vehicles and items of motor vehicle equipment (see 49 U.S.C. Chapter 301). NHTSA does not provide approval of motor vehicles or motor vehicle equipment, and we do not determine compliance of a vehicle or item of motor vehicle equipment outside the context of an actual enforcement proceeding. Instead, manufacturers are required to self-certify that their products conform to all applicable safety standards that are in effect on the date ofmanufacture. FMVSS No. 108 specifies requirements for original and replacement lamps, reflective devices, and associated equipment. The following represents our opinion regarding the applicability of our regulations on your proposed product based upon the facts set forth in your letter and your demonstration of the lamp in a meeting at NHTSA headquarters in Washington, D.C.

    Your letter described a proposed vehicle front lighting system with two headlamps, which you consider to be a "combined headlighting system" under S7.6 of our standard. Your letter stated that this system design would include all of the forward lighting equipment required by FMVSS No. 108 and that it would meet the relevant requirements of the standard for each item (e.g. , meeting S7.4 for the integral beam headlamp and meeting S7.5 for the replaceable bulb headlamp).

    We understand that your proposed system would include an array of six LEDs that would provide the lower beam headlamp illumination and that you believe it would meet the standards lower beam photometric requirements. We also understand that the LED portion of the lower beam would remain activated and contribute toward meeting the standards upper beam photometric requirements. Your letter stated that the upper beam portion of the lamp would have an independent reflector and a replaceable light source, while sharing the same lens and housing with the LED lower beam lamp.

    In your letter, you also expressed your opinion that the LED lower beam portion of the lamp constitutes a single, simultaneously-aimable light source unit, which is part of an "integral and indivisible optical assembly" which includes the lens, reflector, and LED light source. As discussed in the meeting with NHTSA staff, you stated that you consider the array of LEDs to constitute a single light source, because they are wired in a series, such that failure of a single LED causes all of the LEDs to cease operation. You further stated that because the lower beam lamp is an integral beam headlamp, the entire lamp would need to be replaced in the event of a burned out or damaged LED. Furthermore, referencing the definition of "integral beam headlamp" contained in S4 of Standard No. 108, your letter stated that "[t]here is no restriction on the number of light sources useable for the headlamp".

    As you are aware, paragraph S7, Headlighting Requirements, of FMVSS No. 108 requires vehicles to be equipped with one of several permissible headlighting system options, whose specifications are set forth in the standard (i.e. , systems conforming to the requirements of S7.3, 7.4, 7.5, or S7.6). Of relevance here, paragraph S7.6, Combination Headlighting System, provides that such systems "shall be comprised of either two headlamps designed to conform to the requirements of S7.6.2, or any combination of four headlamps designed to conform to the requirements of S7.3.7, S7.4, or S7.5 of this standard".

    Paragraph S7.6.2 states that for combination headlighting systems consisting of two headlamps, each headlamp shall be designed to conform to Figure 17-1 (Photometric Test Point Values for Mechanical Aim Headlighting Systems) or Figure 17-2 (Photometric Test Point Values for Visual/Optical Aim Headlighting Systems) and shall be a combination of two different headlamp types chosen from the following types: a Type F headlamp, an integral beam headlamp, and a replaceable bulb headlamp. A portion of the headlamp that contains an integral beam headlamp must be designed to conform to the requirements of S7.4(c) through (h) of this standard. A portion of the headlamp that contains a replaceable bulb headlamp must be designed to conform to the requirements of S7.5.

    Under paragraph S4, "integral beam headlamp" is defined as "a headlamp (other than a standardized sealed beam headlamp designed to conform to paragraph S7.3 or a replaceable bulb headlamp designed to conform to paragraph S7.5) comprising an integral and indivisible optical assembly including lens, reflector, and light source, except that a headlamp conforming to paragraph S7.8.5.2 or paragraph S7.8.5.3 may have a lens designed to be replaceable". The definition of the term "integral beam headlamp" does not place a limitation on the number of light sources in such lamp. However, under S7.4(b), there are locational requirements which correspond to whether each headlamp has one or two light sources. As we explained in our December 30, 1992 letter of interpretation to Mr. T. Kouchi, we have previously considered lamps with LEDs (which as a practical matter always have multiple LEDs) to have multiple light sources, with each LED constituting a single light source.

    However, the situation where a number of LEDs are wired in series, such that they would operate or fail as a single unit, is different than the ones we have previously addressed. Because you have wired the LEDs as a series, failure of one LED would cause all of the LEDs to cease functioning. Thus, in such cases, we agree that the entire array of LEDs is a single light source, regardless of the hardware involved. Therefore, we believe that a combination headlighting system with an integral beam lower beam headlamp using LEDs would be permissible, if such LEDs are wired in series and allow the headlamp to meet the photometric requirements of the standard.

    We also note that it may be possible for a lower beam headlamp with LEDs to meet the requirements of a different alternative under paragraph of S7.4, Integral Beam Headlighting System, by using beam contributors, each of which would contribute to meeting the headlamps photometric requirements (see S7.4(a)(2) and (d)).

    Your letter also requested clarification regarding what constitutes the "optical center" of a lower beam headlamp, which you suggest should be the geometric center of the portion of the lens that is illuminated by the LED light sources. You argued that this approach would provide the appropriate geometric reference for measuring the "distance to floor and between the lamps" and that it would also serve as an "optical axis" to ensure proper horizontal and vertical aiming of the headlamp, as well as determine a correct alignment to the photometer axis. You seek confirmation that in determining the relative location of the lower beam and upper beam light sources, the "optical center" of the LED lower beam headlamp shall be used and that a design where the optical center of the LED lower beam headlamp is placed most outboard and above the upper beam light source, such lamp would be considered to conform to the requirements of S7.4(b) and (c), as well as S7.5(d)(2) and (3).

    We agree that for LED lower beam headlamps with a clear lens (i.e. , where light passes through the lens without being optically redirected), the optical center should be determined as the geometric center of the portion of the lens that is illuminated by the LED light sources. Over the last several decades, the agency has replied many times to requests for interpretation regarding the center of lamps, but requests have all involved filament bulb lamps. We note that in a 1984 final rule responding to petitions for reconsideration under FMVSS No. 108, the agency referred to "optical center" as the reference center during photometric measurement (see 49 FR 20818 (May 17, 1984)), and in our January 14, 1976 letter of interpretation to the Department of California Highway Patrol, we stated that the center of the emitted light is always taken to be the center of the optical axis.

    In the case of a clear lens LED headlamp, we believe that your recommended approach is consistent with these prior statements. Although not referenced in our standards, we note that the Society of Automotive Engineers (SAE) standard J1889, L.E.D. Lighting Devices, provides two options for determining the "LED lighting device light center". The first option is to determine the geometric center of the total illuminated area of the lamp, and the second option is to determine the geometric center of all of the individual LED light source centers. However, the agency does not believe that the second option is a valid method for measuring the optical center, because it may not correlate to the actual photometric output of the lamp (e.g. , different LEDs could have varying intensities).

    If you have any further questions, you may call Mr. Eric Stas of my staff at (202) 366-2992.

    Sincerely,

    Stephen P. Wood
    Acting Chief Counsel

    ref:108
    d.12/21/05