Wikipedia:Reference desk/Archives/Miscellaneous/2012 September 3

= September 3 =

How does this toy work specifically?
I saw a toy called Leap Frog Tag, an electronic "pen" that you connect to your computer and download the audio for books. Then you buy the book at the store, and when you touch the pen on pictures and words in the book, the word will be spoken or something specific to that picture will be spoken. I suppose something is coded in invisible ink and that the pen emits an IR light beam and depending on how another IR sensor receives a reflected signal, it can tell the code of the image or word to identify what was touched to play the corresponding audio. What is the format of the invisible code? I was thinking it's plausible that every book made has to have a unique number, so each illustration invisible ink code could be book ID/image ID. (no need to encode a page number if every image is numbered). Some illustrations are half a page in size, so the invisible code must be repeatable and stackable. It's also scannable from any orientation. How could an n-bit/m-bit combo be packed into about a 1cm square so that it's scannable from any orientation and distinguishable from its neighbors? 67.163.109.173 (talk) 12:14, 3 September 2012 (UTC)
 * WHAAOE: Tag (LeapFrog). You're pretty much spot on with the 'invisible code' idea: the pen reads a pattern of small dots around the writing to establish what it's looking at. However, there's not much information given by the dots, since the pen simply looks up its position in a database and uses information downloaded over USB to determine the correct action. The patent for the positioning system is here. - Cucumber Mike (talk) 15:56, 3 September 2012 (UTC)
 * See Anoto for an example. I don't know if they specifically use this company's technology, but it is very similar. Take a close look at one of the books and you'll see the pattern. 209.131.76.183 (talk) 12:21, 4 September 2012 (UTC)
 * Reading the article, Tag (LeapFrog) is listed as an example.209.131.76.183 (talk) 12:23, 4 September 2012 (UTC)

Red light Green light
On the show Boss (TV series) votes are tallied in the Chicago city council by placing red or green markers next to the names of the aldermen, green for yea and red for nay. Is this accurate? How long would there be such a tradition of green for yes, and red for no? Chicago has been a major city since long before traffic lights have been around. Do other jurisdictions use this? What is the source of the choice of colors? μηδείς (talk) 20:34, 3 September 2012 (UTC)
 * Railway_signals predate automobile signals, and (often) use the red=stop, green=clear system. There are/were many other systems at play. SemanticMantis (talk) 21:27, 3 September 2012 (UTC)
 * Couple of previous instances of this question: Red=Stop Green=Go, and Why do Westerners use green color for positive and red color for negative. Card Zero  (talk) 18:14, 4 September 2012 (UTC)
 * See Red and Green. I love the first sentences of those articles: "Red is the color of blood and strawberries." vs "Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometers." --Tango (talk) 18:41, 4 September 2012 (UTC)


 * I'll add Blood and Strawberries to my list of potential band names. —Tamfang (talk) 19:06, 4 September 2012 (UTC)


 * The link to the old discussion is interesting, but the best answer is an anonymous unsigend edit with no links or references. μηδείς (talk) 19:20, 4 September 2012 (UTC)