How do gaming console laser guns work?

December 12, 2003 6:17 AM

You know the laser guns that various gaming consoles have - well how do they work exactly? [more inside]

These laser guns are generally attached to the console itself, so how does the tv know where the laser is pointing at any one time?
Possibly a really stupid question, but hopefully someone can help with a link or two. Thanks.

posted by kev23f to technology (11 comments total)

I've always wondered this too. Here's how.
posted by echelon at 6:23 AM on December 12, 2003

Short answer: There's no "laser" involved. The gun is actually an eye of sorts, and it's looking at the TV. It can tell what you're pointing at because the game machine is pretty much just looking at its own output.

At least, this was the case back in the 70s & 80s with input devices called "light pens," and is the principle upon which the Duck Hunt light gun works. (For values of the term "works" which still don't include blasting that stupid dog...)
posted by majick at 6:28 AM on December 12, 2003

It doesn't know. In actuality, the gun doesn't shoot the TV, the TV shoots the gun. There's a sensor in the gun, and when you pull the trigger, it blacks out (or whitens, systems differ) the screen, putting a white (or black) target shape back where it was, and the sensor will tell if your aim is true. As the screen redraws, the delay until the aimed-at position is illuminated can also pinpoint your missed shots. I wondered too when I was I kid. In college, I got turned on to Unca Cecil.
posted by planetkyoto at 6:29 AM on December 12, 2003

I suck.
posted by planetkyoto at 6:29 AM on December 12, 2003

"The gun doesn't shoot the TV, the TV shoots the gun" is possibly the best, most succinct answer to the question I have ever read. Nice turn of phrase!
posted by majick at 6:33 AM on December 12, 2003

Thanks for the replies everyone.
posted by kev23f at 6:45 AM on December 12, 2003

Here's a related question: I always want to buy the lastest version of Time Crisis for PS2, but whenever I pick up the box I see the warning about how you have to buy a whole separate component if you want to use a light gun when your system is hooked up through S-Video or component video cables. Why, damn you, why?
posted by yerfatma at 10:02 AM on December 12, 2003

That's so cool.

I grew up on Duck Hunt and I could never figure this out.
posted by Yelling At Nothing at 10:43 AM on December 12, 2003

I grew up on Duck Hunt and I could never figure this out.

Amen. I was somewhere in the middle of my formal CS education, and learning to actually apply some sort of disciplined critical thinking to abstract situations, when I learned about this, and it was just So Obvious.

As a kid, I had always assumed there was a gyroscope built in to said devices, and an accelerometer, and that these were used to calculate the position and orientation of said devices, which seemed awfully fucking slick (not to mention light-weight) for such cheapo devices.
posted by cortex at 3:36 PM on December 12, 2003

Why, damn you, why?

Apparently it's something to do with signal synchronization, increases accuracy by avoiding unnecessary latency. Makes playing on a decent telly very difficult. Also doesn't work with those double scan 100Hz models.
posted by inpHilltr8r at 4:44 PM on December 12, 2003

When I dug out my old 8-bit Nintendo four years ago or so, I found that during the years it had spent underneath my younger brother's bed, the end of the light gun's barrel had broken off. The missing piece included the part of the barrel that limits the part of the TV screen the gun registers when you pull the trigger, so as a consequence, you could kill a duck in Duck Hunt merely by pointing somewhere in the TV's vague direction. This led to many trick shooting demonstrations on my part (under my leg, behind the back, eyes closed, etc.) before my roommates figured out the trick.
posted by UKnowForKids at 8:11 AM on December 13, 2003