pausch@ra.cs.Virginia.EDU (Randy Pausch) (09/23/89)
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? b) any R&D work has been done in this area? -- Randy Pausch (pausch@virginia.edu) 804-982-2211 Assistant Professor, Computer Science Deptartment, Thornton Hall, University of Virginia, Charlottesville, VA 22903
larry@kitty.UUCP (Larry Lippman) (09/23/89)
In article <PAUSCH.89Sep22174506@ra.cs.Virginia.EDU>, 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? > b) any R&D work has been done in this area? This feature has already been implemented in consumer and other products. I have a Panasonic clock radio which uses a vacuum fluorescent display, whose intensity is controlled not only by a brightness control knob on the side of the radio, but by a photocell. The net effect is that the brightness is directly proportional to the ambient light, within certain limits defined by the control knob setting. Since vacuum fluoresecent displays can be intensity modulated, this is easy to implement. Intensity of LED's can be controlled by varying the duty cycle of the digit-segment multiplexing scheme. In the case of LCD's, most backlighted LCD displays use an electroluminescent panel, the intensity of which can also be easily varied. The earliest device I can recall with variable level of indicator illumination tied to ambient light was a commercial mobile two-way radio, the General Electric MASTR I. I first saw this optional feature around 1969. To answer the second question, I suspect that no R&D work per se has been done in this subject area. If a manufacturer wishes to include such a feature in their product, they simply just do it, since the required engineering is no mystery. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
psfales@cbnewsc.ATT.COM (Peter Fales) (09/24/89)
In article <PAUSCH.89Sep22174506@ra.cs.Virginia.EDU>, 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