POV display

From OpenCircuits
Revision as of 02:08, 26 October 2007 by 47.230.0.45 (talk)
Jump to navigation Jump to search

voli aereo germania asus kit gps per a716 e a730 hinh sex ha kieu anh roof-top.info mesa boogie powerhouse 8x10 rex ap rti 720 orologio da parete moderno dimm sdram pc133 168 pin 512mb index k maro femme like you mp3 download terios daihatsu mary stuart site mario winans feat p diddy i dont wanna k volkswagen auto km 0 km0 ripetitore di segnale antenna homepage pegmatite www macchianera it base lessico hard disk esterno notebook flora efa roof-top.info horizont incontro cannes forno ariston barbecue msn error 81000314 cover cd creazione persone nude giorno di pioggia motori ad alta potenza specifica telecamere wireless home marco borsato en alib rats cori laziali free hillsong page rx v557 photosmart 945 hp chanson instrumental variete americaine venezia valencia page pastamore delonghi worcester gran bretagna acquatici torrecuso guida stazioni radio yokohama coupe hyundai 1 6 fx plus aladino annuncio over the hills and far away led zeppelin yentai personalphoto guida donda olio mandorle dolci hdd 200 maxtor regeneration body fit Gioiello cesare paciotti calcola il qi www latinas com Cerco lavoro capracotta nissan micra 10 16v gp32 blu home hotel samoa www wwe com dave armstrong out of time inqilab com mobilni svet cpi foggia ponte piedini candidi box esterno enermax foto fake di alessia norwalk connecticut url Video negre fin young cannibals panasonic plasma 42 serie 500 la banda del sogno interrotto link mobydick galiero dragostea din tei dj ross radio rmx sesso in daunia microprocessore intel xeon i go again puma speed cat rosa foto annuncio ragazza nokia 86 lettori cd e dvd jvc rita cadilak musiche film il gladiatore variante di valico jeans bond earth wind - re live by request ice climbers panelli mario c sas == POV display ==

A "persistence of vision display" (POV display) has only a single line of LEDs blinking on and off. The display mechanically sweeps it across a person's field of view, giving the illusion of a 2D display.

(Do I need a diagram or a picture here?)

(Nearly all LED displays in microwave ovens and alarm clocks electrically sweep the digits across a person's field of view, giving the illusion that it's displaying all 4 digits of the time "12:55" when actually only one digit is illuminated at any one instant).

User:DavidCary is building yet another "POV display".

I plan on putting a few features into my display that I haven't seen in any other so far:

  • bright blue LEDs (even though blue is usually the most expensive color ... although sometimes "true green" is even more expensive than blue).
  • no slip rings -- just pumping energy across an air gap
  • ... and a few other features that I'm keeping hush-hush.

I want lots of lumens. Unfortunately, when I go to pick LEDs out of the catalogs, they're not rated in lumens, they're rated in candelas.

Is it even possible to estimate "lumens" from the catalog information?

Do you know what the difference is? Does your flashlight really produce 10 times the light ( in lumens)? Or does the flashlight merely focus its light on a tiny spot, so that that spot gets 10 times as many candelas ?

For example, check out these 2 LEDs: $8.75 SSP-LX6144C7UC : 4000 mcd at 120 mA $8.75 SSP-LX6144D7UC : 1800 mcd at 120 mA

From the mcd rating, it appears that the first one is more than 2wice as bright -- and it is, if you're directly in front of it when you look at it. However, if you're even the tiniest bit off-center, the second one is much brighter -- in fact, the total lumens that second LED puts out (2500 mlm) is slightly more than the total lumens than the first one. If you diffuse the light and try to light up a whole room with an array of them, the second one will make the room brighter.

I'm currently planning on using these in my first POV display:

  • $1.32 Telux TLWB7900 : blue : 330 mlm, 231 mcd at 50 mA. (price in ones from http://Newark.com/ )

Other LEDs I considered using in my POV display (and may re-consider for my next one):

  • $18.89 "Lamina light engine" BL-22B1-0140 : 22000 mlm at 420 mA. (this price includes the required heat sink -- price in ones from http://Digikey.com/ ). This has the most lumens per dollar I've found so far (for blue LEDs).
  • $8.750 Sunbrite LuxLEDs SSP-LX6144D7UC blue: 120 mA, 2500 mlm, 1800 mcd (Odd that the red Sunbrite LuxLEDs are cheaper at Newark, the other colors cheaper at Digikey.) cheapest $/lumen blue LED, except for the "light engine"
  • $2.550 Lumex "DSP LED" 67-1876-ND: blue, 5 mm, 2500 mcd ( DigiKey ) apparently have some kind of internal chip. All colors run at 2.0 V nominal (1.5 V minimum) (rather than running on current like most LEDs. unfortunately, the data sheet doesn't suggest how much current they take -- I presume more than 20 mA).
  • $1.600 Sunbrite "based LED" SSP-01TWB7UWB12 (441-1007-ND) blue 10 mm 20 mA 7000 mcd
  • $5.980 GM5WA06270A SMT RGB (35 mA red, 35 mA green, 35 mA blue) 3000 mcd (full color range -- apparently used for digital camera flash ?) (Digikey)
  • Mouser: hi-power LEDs ( http://www.mouser.com/search/refine.aspx?Ntt=LEDs hi-power ) shows "lumens" directly -- exactly what I wanted.

further reading

Spoke-POV and propeller clocks links:


Is this http://led-display-and-design-swicki.eurekster.com/ relevant?

I think so--71.234.233.163 18:06, 22 June 2007 (PDT)