US 5,803,579 · Granted 1998-09-08
The LED Trick That Made Car Lights Look Like Real Daylight
This patent describes a car light made by mixing two different colored LEDs—say blue-green and amber—so that when they overlap, your eyes see them as pure white light. It's like mixing paint colors, except with light beams, and the result is bright enough and high-quality enough to actually light up a road or dashboard.
The plain-English version
What it protects
The claim covers a vehicular lighting assembly where multiple LEDs of different hues are positioned so their light beams overlap and mix to create a perceived white color. Specifically, it protects the arrangement where at least one LED emits one color (like blue-green) and at least one other LED emits a distinctly different color (like amber), and their combined light produces metameric white illumination with sufficient intensity and color rendering to function as an effective light source. Anyone manufacturing a multi-colored LED light that creates white by mixing overlapping beams from differently-hued LEDs in this manner would potentially infringe.
Why it matters
Before reliable LEDs became cheap, carmakers relied on halogen and incandescent bulbs for everything from headlights to interior cabin lighting. This patent from Gentex—a major supplier of automotive lighting and mirrors—showed how to create high-quality white light by mixing LEDs of different colors rather than using a single white LED or a traditional filament. This approach became commercially important as automakers began replacing traditional bulbs with LEDs, and Gentex's innovations in color-mixed LED lighting became part of their competitive advantage in the automotive lighting market.
Real-world use
When you sit in a modern car and the interior lights or instrument panel glow with a crisp white light instead of a yellowish or bluish tint, you may be seeing the result of mixed-color LED technology like this.
Original USPTO abstract
An illuminator assembly, having a plurality of LEDs on a vehicular support member in a manner such that, when all of the LEDs are energized, illumination exhibiting a first perceived hue, e.g., blue-green, and projected from at least one of the LEDs overlaps and mixes with illumination exhibiting a second perceived hue, e.g., amber, which is distinct from said first perceived hue and which is projected from at least one of the remaining LEDs in such a manner that this overlapped and mixed illumination forms a metameric white color and has sufficient intensity and color rendering qualities to be an effective illuminator.
Patent details
- Publication number
- US 5,803,579
- Filing date
- 1996-06-13
- Grant date
- 1998-09-08
- Assignee
- Gentex Corporation
- Inventor(s)
- TURNBULL; ROBERT R., KNAPP; ROBERT C., ROBERTS; JOHN K.
- CPC class
- B60L1/14
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