Arcade style IR gun scoring (With multiple guns)

[DB Tech]

Wondering if anyone out there knows how in theory the arcade style shooting galleries score with multiple shooters. I'm thinking of the type at Great America. If you don't know theory if you can provide a schematic that would be great too. Thanks to all who post.

 

[(*steve*)]

The "gun" is a sensor. It detects where it is pointing by timing the bright point of light it sees as the screen is scanned (requires a traditional picture tube type screen).

Once you know where the gun is pointed when the trigger is pulled you know who shot what.

 

[DB Tech]

I guess I should have been more clear on what I am looking for. The unit I want data on is from the 70s long before the screens of today. I know the units had a light in the gun and each of the targets had sensors in them. With this additional knowledge does anyone know how they managed to differentiate the guns scores from each other? The guns were tethered via data cables.
Thanks

 

[Resqueline]

So you don't mean the arcade games shooting at a CRT screen, but rather shooting at some physical mock-up scene with moving targets?
If it's the former then it's all in the timing (and the cables), and the gun would only have a lens and a phototransistor.
If it's the latter then I guess they may have modulated the different gun LED's with different frequencies, and the targets would have phototransistors.
It's a real easy technique and quite probable, but I have no knowledge of exactly how they did it though.

 

[DB Tech]

The guns had a lamp in them. The targets have a photo-transistor in them. Did they use a simple form of PWM? This was the start of the IC era. I just need to know how they were able to tell the different guns apart. A PIC or ARDUINO controller will be easy to set up to process the data. I plan on using an IR diode with a lens system. The target can be an IR detector or a photo-transistor.
Thanks

 

[Resqueline]

If they employed incandescent lamps then I'm inclined to believe they used a "coincidence" detection. (The timing of trigger & photodiode being the same.)
Small incandescent lamps can be modulated, but only by low frequencies. It is possible to add this method to the timing method for improved discrimination.
For your application with LED's I'd try to use a high modulation frequency, like 30, 35, 40, 45kHz and so on, in addition to timing coincidence.