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US 2007/0182337 A1Published application
Increasing Reliability of Operation of Light Emitting Diode Arrays at Higher Operating Temperatures and its Use in the Lamps of Automobiles
AssigneeHoneywell International Inc.
InventorShanoprasad Kunjappan
Life of this patent
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Abstract
A lamp in which a LED array is coupled to a transistor such that the same amount of current flows through both. The voltage level at the control (e.g., base) terminal of the transistor is controlled such that the current magnitude is reduced when the operating temperature rises. As a result, the heat generated from the junctions of the LEDs in the LED arrays is reduced, thereby compensating for the increase in the operating temperature.
Claims8
A lamp comprising:
- a transistor having a control terminal, said transistor passing a current of a magnitude determined by a voltage at said control terminal;
- a LED array coupled to said transistor, and generating light with an intensity proportionate to said magnitude of said current;
- and
- a driver block coupled to said control terminal and generating said voltage with a first level when an operating temperature of said lamp equals a first value, and a with a second level when said operating temperature of said lamp equals a second value, wherein said first value is not equal to said second value and said first level is not equal to said second level.
1 more element
Dependencies are inferred from the claim text.