Persistence Of Vision Would Make A Great HUD


[Eduardo Zola] has just put the finishing touches on this awesome real-time persistence of vision display which displays text as you type!

It looks like the display is mounted on a small DC fan, which [Eduardo] powers using a bench top power supply. This allows him to fine tune the speed manually, without adjusting the the actual POV controller. The display receives the characters from the keyboard via a small USB RF receiver, and it has got a pretty snappy response time.

There isn’t too much more info on the project, but it certainly gives us an idea — could persistence of vision be used to create a kind of heads up display in a vehicle? What do you think?

We’ve seen tons of cool persistence of vision projects, like this awesome wind powered clock, to even the likes of full color video on a large spinning display!

[via Adafruit]

33 thoughts on “Persistence Of Vision Would Make A Great HUD

  1. I think this is a good technology demo. Adding music to technology demos is a bad idea. Ambient sound would be better. I also think that using POV for heads up displays in vehicles is a bad idea. In fact any kind of strobed display in a moving vehicle is a direct mismatch to human visual perception. New cars using led brake lights use PWM for the brake lights which is very annoying and dangerous. PWM lighting on cars should be banned by the DOT.

    1. I’ve never noticed PWM with the naked eye on brake lights, but I’ve seen the flashing on Top Gear and the like. It seems like it wouldn’t be a big deal to install an inductor in series with the LED driver to filter the PWM and allow the LEDs to be “constant on” when lit.

      1. The flashing you see on cars on Top Gear is a special case. These cars are fitted with systems that detect “emergency” braking. These systems often pick up the type of braking performed on a track as “emergency” braking, and activate the light’s emergency mode, which often involves flashing brake lights and also indicators. This is a new idea many European manufacturers have been working with.

      2. It’s not the flashing that sports cars do when braking hard, that’s a different thing. PWM is used to dim the tail lights for the two different states of not braking and braking on cars that have combined tail and brake lights (most cars?).

        I find it easiest to notice the PWM when the cars are not braking (would make a longer off state) and passing sideways in front of you when they are changing lanes. I have noticed it mostly on Volvo cars but maybe Volvos are just more common here in Sweden.

      1. I never quite understood why they used PWM in the first place. From what I’ve seen brake lights are either “on” or “off”, I’ve never noticed them to have different levels of “on”.

  2. As shown with a handful of characters it complies with the guidelines of 8 per 5 second period. There is no room for such whirling madness under the dash.
    As to strobing tail lights, I think there is a reason for this. They catch averted sight better, and there is something for machine vision cars to definitely ID. In other words the DOT is behind it.

  3. Strobing tail lights should not be banned. I swapped out the tail light on my motorcycle with one that strobes like an ambulance brake lights so it grabs the attention of assholes following too close or not paying attention. Id rather strobe the guy behind me when I grab the brakes and piss him off than get run over and possibly killed.

  4. If it’s late at night, you probably won’t even need anything rotating. Any bright spots are going to burn into your retina for a few milliseconds at least.

    And blue is the worst choice for night vision. You would want it to be red.

  5. Whether POV is a good idea in a vehicle is a good idea or not is debatable, but I’d love to see a POV system that uses both sides of the display (you’re seeing the front in this project) to make a 3-D (or at least depth-enhanced) display with the back side as well.

      1. I remember those……and the headaches that came with them:P

        Don’t get me wrong. I liked how that display worked by using one line of leds to quickly display an image with a moving mirror. The technology just wasn’t quite there yet given the limited color palette those displays provided (if it was we might all be using the Nintendo version of the Occulus Rift for games, VR, shows, Wii U, etc). Now if you were to do that with today’s technology (especially the multi-color leds)……..

        Though something like that might be useful if you could use the windshield as a display surface.

        Something that occurred to me, though really quite impractical, was to rebuild the windshield wipers as a persistence of vision system (see what I meant about impractical?). Granted you would only be able to use this system when it’s raining just hard enough, unless perhaps you modified the windshield wipers further so they didn’t press down on the windshield when it’s not raining. Then there’s replacing the plastic strip with a transparent one with a row of leds underneath protected from the elements……..and all the wiring…….

  6. I like strobing brake lights for all the same reasons, but HUD in a car is a VERY VERY BAD IDEA! The driver’s primary focus while driving a car needs to be what’s out there in the real world, that if you don’t pay attention, you will crash into (or it will seek you out and crash into you, if you don’t take evasive action).. Back in the stone age, when they actually taught kids how to drive, they taught us defensive driving. In other words, look in front of the car. If there’s something there, don’t go there! Having to take your eyes off the road to check the speedo and gauges is quite enough distraction for any normal healthy person; thank you very much. Adding a HUD can only make things worse.

    1. Adding HUD in itself is not a bad thing as long as it is displaying relevant information. The gauge cluster is low enough on my dads truck that i have to look down and take my eyes off the road when i drive it. When it is dark i connect my bluetooth OBD adaptor to his truck and run torque on my phone in HUD mode. I feel much safer that way when all i have to do is change the angle of my eyes a little and not take my eyes off the road completely. Peripheral vision is still useful that way.

    2. The problem isn’t “them” and “they” not teaching kids to drive. It’s all of us choosing to drive with care every day. I’ve been in more near-misses, been cut off, no-signaled, and general-idiot-ed by middle aged men than any other demographic, despite all the jokes about female drivers. I actually got stuck behind a pair of middle-aged men who got OUT of their cars at an intersection to swear at each other for no apparent reason – they didn’t crash or anything, it was weird.

      Anyway, being able to look THROUGH the gauges might actually be interesting – except for those with poor ability to change their focus between distance and near. Anyone with bifocals would have a hard time with a windshield HUD that wasn’t in the lower periphery of the windshield.

      1. I don’t know… I have a GMC with factory HUD, and I wear bifocals. The HUD appears to be 25-30 feet in front of the car. (so, yeah, it’s pretty low in the windshield) It’s pretty well done and is clearer to me than the actual dashboard gauges.
        It shows only about 3 things at a time (selectable). If it was busier, it might be more of a distraction, but I think it’s pretty good as it is.

    3. The holy grail even with HMDs has been to project the image so that it appeared at a distance. That’s one major limitation with replacing reality with virtual reality. Our minds know we are looking at something close up and flat, regardless of how “3D” the graphics are.

      1. I’m sure many of us remember the sunglasses in the 80s with writing on them. In normal use, you never even noticed the writing. But if you focused closely you could see it.

        When HUDs were first coming out, the intention was to project onto the windshield, and have a separate screen closer to the driver which picked up the reflection. That distance between the screen and the windshield would create a sense of depth.

        I’m sure you have noticed the difference looking at a glass mirror (rear surface) vs a metal mirror (front surface), and maybe even glass mirrors of different thicknesses.

  7. Would a persistent display be quickly visible under stressful conditions, or in the seconds around a sudden incident? (wondering if the drivers perception of time or vibration effects could hamper the display?)

  8. Not sure there’s a great application for using a low resolution POV display reliant on moving parts for a vehicle HUD, it’s probably much better to get some 7-seg LEDs, etc, or a full LCD, like most existing vehicle HUDs on the market.

  9. This is about the worst idea for a HUD – blinding yourself with flashing, moving, bright blue LED’s. It pretty much fails all the criteria for ways to display information to a driver.

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