View Full Version : NES Zapper a no-no on Flat Screens?

02-23-2003, 01:02 PM
I just realized my Zapper isn't working with my HDTV flat monitor. This is the first time I've tried to use a Zapper with my HDTV and I had no idea that it wouldn't function right on it. I thought maybe the Zapper was screwed up, so I hooked up the NES to an old 21 inch conventional tv set and it worked perfect.

Anyone know the technical aspects of why a Zapper won't work on a flat screen? I would imagine it has something to do with the lens on the zapper being curved.

02-23-2003, 01:31 PM
No, I think it might be an issue with light guns and HDTV's in general. I know the Xbox blaster won't work on HDTV's either.

02-23-2003, 01:41 PM
Hmm, I'm surprised the Zapper won't work on an LCD. The way it works, it identifies what frame in which it's seeing light, rather than figuring where the electron gun is at the exact point it sees the beam pass by. In other words, it's far less precise than modern light guns. I guess LCDs are too slow, even for something like that.

02-23-2003, 01:46 PM
this is a double post, so um...

I eat live fish.

02-23-2003, 01:47 PM
Well, flat screens aren't really flat. They mold glass around the convex tube, and do it in such a way that the image refracts into a flat screen. At least this is the way they do some of the monitors, like computer monitors. If you have a Sony Vega (which I think is a true flat screen) then I don't know. otherwise it could be that the refraction built into the glass may be causing trouble. It could also be polarized, meaning to the zapper it's always black. try holding the zapper sideways.

02-23-2003, 01:55 PM
actually i dont think it has anything to do with flat screens, i think it has something to do with the screen not being 480 lines interlaced...


02-23-2003, 02:44 PM
Wb...I believe you're right. Light guns don't work on lcd's, three-color projectors and hdtv's. The way the light comes off is different on these types of tv's.

02-23-2003, 03:52 PM
Okay, let me see if I've got my tech info straight.

A light gun has a simple photo transistor near the breach end. The muzzle has a lens to spread the incoming light, so that the light gun "sees" as small a section of the screen as possible. When light strikes the photo transistor, the timing information can be used to calculate where the gun is pointing.

Most modern guns are fast enough to read light mid frame, and determine the position of the electron gun when the trigger is pulled. This allows the gun to address virtually any point on the screen. The screen still must be flashed white so that the image is intense enough for the gun to read.

The NES zapper is only accurate to a single frame, which is why the screen is blacked and each possible target is displayed in turn as a white rectangle. Finally, the remainder of the screen is flashed white, to determine if the gun was at least pointed at the screen. Based on when the gun saw light, the NES can determine what target was hit.

If this is all correct, then an LCD wouldn't work for one of two reasons. It's possible that the screen's backlight is not strong enough to register the gun's photo transistor. However, I suspect that the malfunction is caused by the slight delay in most LCDs. Light guns rely almost completely on fine grained timing, so if the screen is even slightly late, the game system will think the gun is somewhere completely different.

I kind of doubt that polarization would have an effect, since as far as I know, light guns have no polarizing filter.

02-23-2003, 05:22 PM
now how about PS guns and that, is it all the same?

02-23-2003, 05:44 PM
I think the principles are basically the same for each gun. The gun can tell the game when it's seeing light, and the software can use that information as it pleases. The potential accuracy is probably limited by the clock frequency of the gun hardware and the bit rate of the controller ports, but that's just a guess.

Alex Kidd
02-25-2003, 01:01 PM
I'm no electrical engineer... powering light bulbs from Oranges still amazes the pants off me... but I think I can understand what you guys are saying about how the light guns were originally designed for CRT Picture Tubes...
But one thing that hasn't been mentioned yet.. how about the Menacer for the Genesis or the Super Scope for the SNES... those have the little infra red receiver... would THOSE work where the NES Zapper and SMS Phaser will not?

Alex Kidd

Whatever happened to "gun games" anyway? the SMS had quite a few as did the NES... and the arcades are full of em... yet the Menacer was practically abandoned with only 2 carts for it (as sega did with almost EVERY perephial). and the Super Scope didn't have many... about 10 or so carts was it? (including the pack in 6 pack game as one cart)
and then the since the start of the 32 bit era on there have been virtually none!

02-25-2003, 01:13 PM
I'm fairly certain that the TV set box for the Super Scope and Menacer is simply a cord eliminator. The guns still read off of the screen. It would be impossible for the gun to obtain two dimensional coordinates with only one sensor. Basically, the gun just uses the IR receiver to get the information to the game system.

Now, to save everyone the trouble of asking, I'll mention arcade light gun games that use projection screens of over 50" in size. These are different light guns that don't read the screen at all. Look very carefully around the black monitor bezel. On Sega games at least, there are over a dozen IR windows. I'm not sure if they send or receive (though I suspect they're receivers,) but they are used to determine the position of the gun through means I won't pretend to understand. It seems like this would be amazingly accurate, but the games are always horribly miscalibrated for some reason. Weird. Maybe the arcades installed poorly made replacement guns.