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1. (WO1985004537) AN LED DRIVER CIRCUIT
Latest bibliographic data on file with the International Bureau

Pub. No.: WO/1985/004537 International Application No.: PCT/US1985/000303
Publication Date: 10.10.1985 International Filing Date: 21.02.1985
IPC:
H03K 17/0412 (2006.01) ,H03K 17/78 (2006.01) ,H04B 10/155 (2006.01)
H ELECTRICITY
03
BASIC ELECTRONIC CIRCUITRY
K
PULSE TECHNIQUE
17
Electronic switching or gating, i.e. not by contact-making and -breaking
04
Modifications for accelerating switching
041
without feedback from the output circuit to the control circuit
0412
by measures taken in the control circuit
H ELECTRICITY
03
BASIC ELECTRONIC CIRCUITRY
K
PULSE TECHNIQUE
17
Electronic switching or gating, i.e. not by contact-making and -breaking
51
characterised by the use of specified components
78
by the use, as active elements, of opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
H ELECTRICITY
04
ELECTRIC COMMUNICATION TECHNIQUE
B
TRANSMISSION
10
Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
12
Transmission through light guides, e.g. optical fibres
14
Terminal stations
152
Non-coherent direct-detection systems
155
Transmitters
Applicants:
AMERICAN TELEPHONE & TELEGRAPH COMPANY [US/US]; 550 Madison Avenue New York, NY 10022, US
Inventors:
LISCO, Richard, Joseph; US
Agent:
HIRSCH, A., E., Jr. @; Post Office Box 901 Princeton, NJ 08540, US
Priority Data:
594,21928.03.1984US
Title (EN) AN LED DRIVER CIRCUIT
(FR) CIRCUIT DE COMMANDE DE DIODE ELECTROLUMINESCENTE
Abstract:
(EN) A driver circuit turns an LED 'on' and 'off' in response to input logic 'one' and 'zero' data signals. A current regulator (11) is series coupled with the LED and serves to maintain a constant current to the LED over time, temperature, and supply voltage variations. During turn-off, this current is shunted away from the LED by a low impedance emitter follower (Q3), operated in the active non-saturated region, and a small reverse bias potential is momentarily applied to the LED which quickly sweeps out the charge stored in the LED junction. At the end of the 'off' cycle there is a forward prebias potential across the LED. During turn-on, the current shunt is reverse biased and a current peaking circuit (14) provides a momentary additional current through the LED. This instantaneous forward current peaking and the forward prebias both serve to substantially reduce the turn-on delay and rise time of the optical drive signal. The current peaking and current shunting circuits are driven from the same differential amplifier (Q1 and Q2).
(FR) Un circuit de commande met une diode électroluminescente (DEL) sous tension et hors tension en réaction à des signaux de données d'entrée comportant des "1" et des "0" logiques. Un régulateur de courant (11) est couplé en série avec la DEL et permet de maintenir constant le courant appliqué à la DEL, indépendamment des variations dans le temps de la température et de la tension d'alimentation. Pendant la période "hors tension", ce courant est détourné de la DEL par un émetteur cathodyne à faible impédance (Q3), fonctionnant dans la région active non saturée, et un faible potentiel de polarisation inverse est appliqué momentanément à la DEL, balayant rapidement la charge stockée dans la jonction de la DEL. A la fin du cycle "hors tension" on applique un potentiel de prépolarisation en sens direct à travers la DEL. Pendant la mise sous tension, la dérivation de courant est polarisée de manière inverse et un circuit d'augmentation de la pente du courant (14) applique un courant supplémentaire momentané à travers la DEL. Cette augmentation instantanée de la pente du courant en sens direct, ainsi que la prépolarisation en sens direct, permettent de réduire considérablement le retard de mise sous tension et le temps de montée du signal optique de commande. Les circuits d'augmentation de la pente du courant et les circuits de dérivation du courant sont commandés par le même amplificateur différentiel (Q1 et Q2).
Designated States: JP, KR
Publication Language: English (EN)
Filing Language: English (EN)
Also published as:
KR1019867000082