Interpretation ID: nht95-7.6

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 fails. 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 output 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 is 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.