Interpretation ID: nht95-4.39

TYPE: INTERPRETATION-NHTSA

DATE: September 29, 1995

FROM: Guy Dorleans -- International Regulatory Affairs Manager, Valeo

TO: Chief Counsel, NHTSA

TITLE: NONE

ATTACHMT: Attached to 11/09/95 letter from Samuel J. Dubbin to Guy Dorleans (Std. 108)

TEXT: Dear Sir:

The use of light-emitting diodes brings technical solutions to almost all the styling trends, and allows to obtain an even patch luminance on the whole extension of the light-emitting surfaces. The sketches hereunder examplify a new area of freedom for rear end lighting:

Functions: Tail, Stop, rear turn signal

[ILLUSTRATION OMITTED -- SEE ORIGINAL SOURCE]

All the LEDs are red in color. The internal wiring is such that failure of one LED does not switch off a complete array of diodes: if we suppose that the system incorporates a total 32 diodes. The diodes will still be in operation if a single diode fai ls. In cases C, C', D and D' [ILLEGIBLE WORD], Standard 108 revised as of October 1, 1994 shall consequently apply in its relevant figure 1b for one lighted section.

Case A: During daytime, when neither the service brake nor the turn signal is operated, all the LEDs are off and no lighting function is used.

Case B: At night, the tail lamp is on, but neither the service brake nor the turn signal is operated. The whole light-emitting surface is slightly glooming, enough to fulfill the optical specifications of Standard 108 for tail lamps. All the diodes are energized at low-level intensity.

Case C: When braking at night, the current in the diodes is increased, so that the sum of the photometrics of the stoplamp and the tail lamp is fulfilled. The whole light-emitting surface is glooming. All the diodes are energized at full intensity. At point HV, the light output is at least fivefold bigger than in case B.

Case C': When braking during the day, the current in the diodes is increased, so that the photometrics of the stoplamp is fulfilled. The shole light-emitting surface is glooming. All the diodes are energized at full intensity. At point HV, the light o utput is at lease fivefold bigger than in case B.

Case D: When changing direction at night, the whole light-emitting surface is glooming. All the diodes are energized at full intensity during the on-period of the turn signal. The sum of the photometrics of the rear turn signal lamp and the tail lamp i s then fulfilled and at point HV, the light output is at least fivefold bigger than in case B. During of off-period of the turn signal, the diodes receive the same intensity as in case B, which corresponds to tail lamp only.

Case D': When changing direction during the day, the diodes are energized at full intensity during the one-period of the turn signal and then the whole light-emitting surface is glooming. The photometrics of the rear turn signal lamp is then fulfilled. During the off-period of the turn signal, the diodes are not energized.

We hereby ask confirmation that this new lighting combination is correct.

Best Regards.