Path: utzoo!attcan!uunet!ginosko!ctrsol!emory!att!cbnewsc!psfales
From: psfales@cbnewsc.ATT.COM (Peter Fales)
Newsgroups: sci.electronics
Subject: Re: consumer electronics question
Message-ID: <3403@cbnewsc.ATT.COM>
Date: 23 Sep 89 18:55:55 GMT
References: 
Distribution: sci
Organization: AT&T Bell Laboratories
Lines: 24

In article , pausch@ra.cs.Virginia.EDU (Randy Pausch) writes:
> 
> A student is interested in looking at variable-intensity L.E.D displays for
> consumer electronics (i.e. your clock radio knows how bright to make itself,
> based on the ambient light in the room).  Does anyone know if
> 
> a) this is already marketed in a commercial project?

My clock radio has a day/night switch that reduces the intensity of the
display.  It does not sense the room light automatically, but this seems
like a logical next step.

> b) any R&D work has been done in this area?

I don't think there is anything particularly difficult about building
variable intensity LEDs.  Reducing the current (i.e. greater series resistance)
should do it.  Pulsing the display and varying the duty cycle is another
alternative that might lend itself better to a digital implementation.

-- 
Peter Fales			AT&T, Room 5B-420
				2000 N. Naperville Rd.
UUCP:	...att!peter.fales	Naperville, IL 60566
Domain: peter.fales@att.com	work:	(312) 979-8031