Vision

LED's pulsed for say 200% of their 'normal' current at a 50% duty cycle appear brighter than 100% current for 100% duty cycle even though the maths says that it's all the same average current. Provided the refresh rate is sufficiently high. Your eye retains an image for ~ 1/60th second. If you go slower than this, the image fades and you can perceive the flicker. If you go faster, the decay rate is such that it can appear brighter. This may have been the reason for the choice of 60 cps AC power line.

The attack time is significantly shorter than the release (or decay) time, making the eye tend to be a peak sensing device rather than an RMS detector. The human eye is responsive to the peak value of illumination. It is assumed here that the pulses have a repitition rate greater than 24 pulses per second. Otherwise, the perceived intensity is also a function of the repetition rate. Above about 40 pulses per second this perceived increase in brightness levels out and is no longer a factor. this varies greatly between men and women, eye (and hair!) color (melanin content), age, and heritage.

Follow the black dot

James Cameron  has written up a few of his PIC projects for Technical Aid to the Disabled. http://quozl.us.netrek.org/ has the pictures and schematics.

Wearable Displays

Ideas for CAPTCHA's

BioMetrics@ Displays@ Speech@ DSP@ Keyboard@  Mouse@ Sensors@ Cameras@ PDAs@

See also:

• http://wearcam.org/
• http://genesis.eecg.toronto.edu/wearhow/index.html
• http://research.compaq.com/wrl/projects/itsy/itsy.html
• http://wearables.www.media.mit.edu/projects/wearables/
• http://eyetap.org/wearable/index.html
• Wearables webring
• The Unoficial Virtual Boy home page
• http://www.gvu.gatech.edu/ccg/
• LCD Key Switches
• Byte Craft A Touch Sensitive Circuit
• Quantum Research Group. QProx One chip proximity sensors.
• Niall Murphy's Embedded User Interface Home Page
• Sharp palm-top/hand-held and Sharp Wizard to RS232 converter
• Don Norman  "The Psychology of Everyday Things" or "The Design of Everyday Things"
• National Institute for Standards and Technology - Information Technology Laboratory - Information Access & User Interfaces
• http://www.bik.com/ occupancy sensor
• http://www.onhandpc.com

Suppliers

• http://www.tekgear.ca/ all parts
• http://www.mindflux.com.au/ "I-Glasses"
• http://www.kopin.com/html/cyberdisplay.html 320x320 b/w $75 to 120.

PICList 2008 contributors: o List host: MIT, Site host massmind.org, Top posters @20081203 Apptech, Jinx, Xiaofan Chen, olin piclist, Vitaliy, William \Chops\ Westfield, Tamas Rudnai, JonnyMac, Alan B. Pearce, Gerhard Fiedler, * Page Editors: James Newton, David Cary, and YOU! * Roman Black of Black Robotics donates from sales of Linistep stepper controller kits. * Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters. * Monthly Subscribers: Shultz Electronics, Timothy Weber, on-going support is MOST appreciated! * Contributors: Richard Seriani, Sr.

  .