(19) United States
(12) Patent Application Publication (io) Pub. No.: US 2002/0043943 Al
Menzer et al. (43) Pub. Date: Apr. 18,2002
(54) LED ARRAY PRIMARY DISPLAY LIGHT SOURCES EMPLOYING DYNAMICALLY SWITCHABLE BYPASS CIRCUITRY
(76) Inventors: Randy L. Menzer, Redmond, WA
(US); Jacques M. Dulin, Morgan Hill,
Jacques M. Dulin, Esq.
Innovation Law Group, Ltd.
851 Fremont Ave.
Los Altos, CA 94024 (US)
(21) Appl. No.: 09/849,027
(22) Filed: May 4, 2001
Related U.S. Application Data
(63) Non-provisional ol provisional application No. 60/239,415, filed on Oct. 10, 2000.
(51) Int. CI.7 H05B 37/00
(52) U.S. CI 315/291; 315/185 R
The invention comprises use ol Dynamically Switchable Bypass (DSB) elements in association with one or more Light Emitting Diodes (LEDs) in arrays lor illumination circuits to provide rugged, reliable lighting. The DSBs are selected from Transient Voltage Suppressors, including Silicon, Metal Oxide Varistors, and Multi Layer Varistors as well as Zener Diodes. The DSBs are not used as circuit protecting devices, but rather as alternative paths for electric current to bypass failed LEDs. Bi-directional TVSs are used as alternative electric paths for circuits using Alternating Current (AC) and parallel LED arrays that light on both phases of AC. Zener Diodes are used in parallel to, but in the opposite polarity orientation to, one or more LEDs in DC or rectified AC circuits. The inventive paired DSB/LED elements overcomes the black-out problems of prior series LED illumination systems, making possible the use of robust LEDs in illumination systems where reliability, long life, low power consumption, low heat output, resistance to shock, vibration, and humidity, and self-diagnosis are important. The DSB elements have breakdown voltages slightly higher than the LED(s) they support, so that when an LED fails, the conduction through the DSB begins. Because the conduction voltage of the DSB so nearly matches the conduction voltage of the LED(s), the remainder of the circuit continues to function as normal. The system is self-diagnostic in that any LED failure presents itself as a dark LED rather than as a whole string of dark LEDs. DSBs may be used with incandescent bulbs.