Use old LCD shutter glasses with a modern video card and LCD monitor w/flicker? - Page 1
Forum section: electronics / projects

author: cdev
author_rank: Super Contributor
timestamp: December 20, 2020, 01:40:45 pm
content: Hi,For ages I have had a pair of LCD glasses (SimulEyes) that supported two old DOS games, and have hoped to someday be able to wire them to work with a modern 3D card. At a hardware level itsmy understanding that most do support it. But either a newer monitor with a very fast refresh rate or a CRT is recommended.I have a (21 inch, 90+ lb) CRT in my basement, (its a hernia making monitor) and that is supported, but before I go to the extreme trouble of dealing with that, I'd like to get it working on my LCD, which is new, fast but just has a 70 Hz maximum refresh rate. (Its an Acer Nitro with AMD FreeSync, it cost $90 new, and the picture is quite decent, and there is virtually no bezel which is kind of cool.)I know its going to flicker.I am just trying to get a feel for the technology. I did verify that the glasses worked when I first got them under DOS, a very long time (several computers) ago.I have two semi-decent last generation video cards, both Nvidia (GTX-1070) and AMD (Polaris family) I could use either.Another alternative is Raspberry Pi which has a lot of GPIOs with no latency issues there at all.That might be a good tinkering friendly intro to the LCD glasses, also. as I'm expecting to have to use an external signal to toggle them and interface to it, GPIO seems likely to be more available. My monitor supports both HDMI and VGA.There is very little on DIYing these shutter glasses thats new online. But I suspect they are basically the same as other similar glasses at the hardware level. They also have a dongle that supports VGA (the dongle senses the value of a single pixel in the corner of the frame and uses that to toggle the eyes)Presumably, I'm looking for a way to toggle the two eyes image in sync with the alternating video frames andprovide a logic signal to the glasses, and be able to adjust the interpupillary distance (a config file is fine for that since i don't anticipating that changing much.)I have several ways to generate and receive interrupts but because of the USB latency issue I suspect serial port (my computer has a real serial port) (or on RPI, GPIO) is likely the best way to go.Have any of you ever done anything DIY like this with LCD shutter glasses?

author: richard.cs
author_rank: Super Contributor
timestamp: December 20, 2020, 01:55:42 pm
content: Connect the monitor via VGA and then derive your glasses sync signal from the VSYNC? It seems more robust than trying to twonk serial port pins in software in line with the frame rate, you just have a left/right ambiguity to solve which could be done manually (flip a switch if it looks weird).

author: cdev
author_rank: Super Contributor
timestamp: December 20, 2020, 02:11:35 pm
content: So, then I just need to use my DB-9 breakout box, wire it"straight through" and break out the vsync pin which its easy to find the pinout for, maybe invert the signal, thats easy! Thank you.Anyway, I'll report back here how this goes.

author: richard.cs
author_rank: Super Contributor
timestamp: December 20, 2020, 04:28:21 pm
content: I don't know what sort of signal the glasses expect, you might have to clock a flip flop with it or similar to generate a left/right signal for the glasses. The Vsync is a brief pulse once per frame.

author: Renate
author_rank: Super Contributor
timestamp: December 20, 2020, 04:38:15 pm
content: Quote from: cdev on December 20, 2020, 01:40:45 pmYou're taking quite a narrow-minded viewpoint there.There are many members on this forum for whom the interpupillary distance is quite variable.

author: ConKbot
author_rank: Super Contributor
timestamp: December 21, 2020, 02:26:13 pm
content: Make sure they are compatible with the polarization of the LCD before you sink too much time into the project.If the LCD and glasses both use linear polarization, then one eye will always look like garbage. If the LCD and glasses use a mix if circular and linear polarization, then you should be able to use it.If the shutter glasses just default to the transparent state, look at the LCD through them, tilt your head some to see if it behaves.

author: cdev
author_rank: Super Contributor
timestamp: December 21, 2020, 09:35:06 pm
content: This web page contains some of the info I'd need to know to use #D shutter glasses with Nvidia on Linux. It contains a few other links too.I have a Linux system and basically, am only interested in doing this if I can use Linux, and since I am unlikely to buy a 120 Hz monitor just for this right now, with my current monitor, I need to be able to use it at a lower framerate. Ideally 70 or 60 Hz.http://users.csc.calpoly.edu/~zwood/teaching/csc572/final11/rsomers/This is a retrofit for VGA shutter glasses but the drivers also need to be available.http://www.int03.co.uk/crema/hardware/stereo/My glasses were actually made by StereoGraphics which makes high end glasses but they were a much cheaper product (SimulEyes) and I dont know how successful they were.Most of those sold probably ended up going to experimenters but that was literally more than a decade agoHere is an interesting video where the person uses electrical impulses to open and shut the eyes rather than LCD shutters. Do you think this is real, or a joke?