Global Patent Index - EP 1075706 A1

EP 1075706 A1 2001-02-14 - MAINTAINING LED LUMINOUS INTENSITY

Title (en)

MAINTAINING LED LUMINOUS INTENSITY

Title (de)

ERHALT DER LED LEUCHTINTENSITÄT

Title (fr)

MAINTIEN DE L'INTENSITE LUMINEUSE DE DIODES ELECTROLUMINESCENTES (LED)

Publication

EP 1075706 A1 (EN)

Application

EP 98918770 A

Priority

US 9808432 W

Abstract (en)

[origin: CA2328439A1] A circuit for maintaining the luminous intensity of a light emitting diode (LED) (12) comprising at least one light emitting diode (LED) (12) for producing a luminous intensity; a sensor (22, 24) for sensing a condition proportional to the luminous intensity of the LED (12) and for producing a luminous intensity signal; a power supply (16) electrically connected to the LED (12) for supplying pulses of electrical energy to the LED (12); and wherein the power supply (16) includes a switching device responsive to the luminous intensity signal for adjusting the electrical energy supplied by the pulses per unit of time to adjust the average of the current passing through the LED (12) to maintain the luminous intensity of the LED (12) at a predetermined level. In one instance, the sensor (22) includes means for sensing changes in the operating temperature of the LED (12). In a second instance, the sensor (24) includes means (28) for sensing changes in luminous output of the LED (12). The electrical energy supplied by the pulses per unit of time are adjusted by anyone of (1) varying the frequency, (2) varying the width of the pulses, (3) a combination of frequency and width, or (4) adjusting the phase of the pulses within an a.c. sinusoidal wave form.

IPC 1-7 (main, further and additional classification)

H01J 40/14

IPC 8 full level (invention and additional information)

G03B 7/08 (2006.01); H01J 40/14 (2006.01); H05B 33/08 (2006.01); H05B 39/04 (2006.01)

CPC (invention and additional information)

Y02B 20/14 (2013.01)

Designated contracting state (EPC)

DE ES FR GB IT

EPO simple patent family

CA 2328439 A1 19991104; EP 1075706 A1 20010214; EP 1075706 A4 20010718

INPADOC legal status


2002-11-27 [18D] DEEMED TO BE WITHDRAWN

- Effective date: 20020524

2002-01-02 [17Q] FIRST EXAMINATION REPORT

- Effective date: 20011113

2001-07-18 [A4] SUPPLEMENTARY SEARCH REPORT

- Effective date: 20010605

2001-07-18 [AK] DESIGNATED CONTRACTING STATES:

- Kind Code of Ref Document: A4

- Designated State(s): DE ES FR GB IT

2001-07-18 [RIC1] CLASSIFICATION (CORRECTION)

- Free text: 7H 01J 40/14 A, 7H 05B 33/08 B, 7H 05B 39/04 B, 7G 06K 11/08 B, 7G 03B 7/08 B

2001-02-14 [17P] REQUEST FOR EXAMINATION FILED

- Effective date: 20001002

2001-02-14 [AK] DESIGNATED CONTRACTING STATES:

- Kind Code of Ref Document: A1

- Designated State(s): DE ES FR GB IT