Electrical transmission or interconnection systems – Personnel safety or limit control features – Interlock
Patent
1984-03-28
1986-02-18
Miller, Stanley D.
Electrical transmission or interconnection systems
Personnel safety or limit control features
Interlock
307270, 307300, 307297, H03K 301, H03K 333
Patent
active
045715068
ABSTRACT:
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).
REFERENCES:
patent: 3968399 (1976-07-01), Jarett
patent: 4425515 (1984-01-01), Larson
patent: 4485311 (1984-11-01), Goerne et al.
AT&T Bell Laboratories
Davis B. P.
Miller Stanley D.
Mullarney John K.
Roberts Patrick E.
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