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INTERIOR LED LIGHTING WITH TEMPERATURE DEPENDENT DRIVE CURRENT

IP.com Disclosure Number: IPCOM000016770D
Publication Date: 2003-Jul-14
Document File: 3 page(s) / 68K

Publishing Venue

The IP.com Prior Art Database

Abstract

A control system is provided for an LED lighting system in a vehicle interior. The control system includes a circuit having electronics that monitor ambient temperature within the vehicle and automatically reduces electrical current to the LED lighting system when the ambient temperature within the vehicle exceeds a predetermined level indicative of a high temperature condition. The reduction in electrical current to the LED lighting system during a high temperature condition is intended to prevent or minimize damage or deterioration of the components of the LED lighting system, and permit the LED lighting system to operate at full illumination when a high temperature condition does not exist.

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INTERIOR LED LIGHTING WITH TEMPERATURE DEPENDENT DRIVE CURRENT

Abstract

         A control system is provided for an LED lighting system in a vehicle interior. The control system includes a circuit having electronics that monitor ambient temperature within the vehicle and automatically reduces electrical current to the LED lighting system when the ambient temperature within the vehicle exceeds a predetermined level indicative of a high temperature condition. The reduction in electrical current to the LED lighting system during a high temperature condition is intended to prevent or minimize damage or deterioration of the components of the LED lighting system, and permit the LED lighting system to operate at full illumination when a high temperature condition does not exist.

Background

         It is generally know to provide a lamp in a vehicle to illuminate the interior of the vehicle during operation of, or access to, the vehicle during conditions of general darkness. Such lamps may be provided as dome lamps, courtesy lamps, cargo lamps, etc. and may use white light emitting diodes (LEDs) as a light source. However, operation of such white LEDs during high temperature conditions (e.g. greater than 60 degrees C) within the vehicle may cause accelerated deterioration or failure of the LED or other components of the LED lighting system. In automotive applications, ambient temperatures within a vehicle may typically reach temperatures of 85 degrees C or more.

         Typical design practices for development of such LED lighting systems for use in vehicles often will reduce the amount of electrical current (e.g. LED forward current) in an attempt to ensure that the temperature of the LED does not exceed certain maximum threshold temperature limits specified for the LED. However, such limitation of LED forward current (e.g. "derating") results in a reduction of light emitted from the LED and often requires the use of additional LEDs to provide a sufficient amount of light for the lighting application than would otherwise be required in non-derated applications. Accordingly, it would be advantageous to provide a control system for an LED lighting system that regulates the amount of electrical current provided to the LED lighting system so that when the ambient temperature is below a

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predetermined value, the forward current is not derated, and when the ambient temperature is above the predetermined value, the forward current is derated in an amount sufficient to maintain the temperature of the LED below the maximum threshold temperature requirement.

Description

         According to one embodiment of the present invention, a control system for an LED lighting system for a vehicle interior is p...