Well, Cecil, you answered a long standing question of mine- the one about the light guns. Two things, though:
Some older touch screens worked by a cross-lattice of photocells or something of the sort, placed in the bezel. But modern ones generally work by detecting pressure on the screen by feeling it twist at the upper and lower, and left and right edges, usually using the piezoelectric effect somehow.
Close-up light pens (as opposed to game guns), which used to be quite common, work by detecting the exact instant the electron beam passes under them.
So not all screens can do it?
No. I haven’t looked at the price of touch screens lately, but they used to cost about $200 than a similar non-touch screen. I dare say the premium is somewhat less now, but it definitely means extra hardware.
The column being discussed here was not available online until today. In Nintendo’s “Duck Hunt,” how does the TV know when you’ve hit a duck?
Please note that if you would like to post a link to a column that is not yet online, the format is http://www.straightdope.com/columns/YYMMDD.html where YY is the last two digits of the year (01), MM is the month (05) and DD is the release date of the column (11). New columns are always released on a Friday.
Wouldn’t it be nice if new columns were released online on the earliest date which they can be published in hard copy by the newspapers? Just a suggestion.
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When I have played these games I certainly could see the screen go dark and then a white square about where the duck was the the screen again.