PSP light pen - possible?

Is it possible to use light pens on lcd type screens?

I was thinking that this would be a cheap and easy thing to make and connect to the psp for touch-screen and mouse emulation.

When i was at school , many many years ago and before computer mice, a friend of mine made a light pen to use on "bbc b micros". All it was was a biro case full of electrics with a wire coming out of it that plugged straight into the back.

This worked by sensing the crt screen updating, but do lcd screens update in the same way or does the whole screen update at once?

I would ask my mate more about it but he hung himself shortly after.

I don't think so, but I really have no idea.

If it is possible it will be possible to play ds games ;)
but i dout it

not going to work

LCDs don't refresh the same way that the CRTs do. They're too fundamentally different for a light pen to work.

and also, PSP's have a fundimental flaw in the screen.. see, PSP's have a very poor quality screen.. the pixels of the screen take a very long time to turn colors, (you can see this as tearing on fine lines displayed moving) which would give an inacurate reading by anything, because as a red pixel turns to blue, it will go from red, to purple, to blue.. which will make it so the pen would pick up the purple also, and that would confuse the crap out of the sensor...

on a CRT, this doesent happen, because the colors can change instantly..

another example is, try to play duck hunt on an LCD screen, it doesent work... for the same reason stated above...

and on a final note... QUIT TALKING ABOUT DS ON PSP! its never going to happen, computers cant even emulate DS yet, and PSP cant even handle SNES games... so its not going to happen....

PC can emulate DS, PSP can handle SNES roms :D

but clip-on transparent touch panel via USB or remote is more like possible..

never the less, this is a brilliant idea

you could work for sony;)

good job lol