Sunglasses that block out glare with lcd spot
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- Douglas Adams, The Restaurant at the End of the Universe
I was concerned that the geometry calculation requires your pupil to be at a precisely known location, but in practice, if it was off, you'd just adjust the sunglasses (and maybe the temples can be made so that you feel their position). You'd calibrate them when you first use them. Of course, the black-spot can be made a little overlarge, for margin of error.
Larry Niven (surely not the only one) mentioned this idea in Grendel (in the Neutron Star collection), a 1968 shortstory, which included [MINOR SPOILER] an update on the old fighter-pilot tactic of attacking out of the sun - which with these sunglasses, is hidden by the black-spot.
The pane is very close to the eye, so small changes are amplified if lines are extended outward into the scene being viewed.
Actually, to be more accurate, it wouldn't depend on the location of the pupil, but on the center of the eye (because the geometry is that when the eye looks in different directions, it rotates about this center). The pupil moves quite a lot, as you glance left and right.
That's going to be difficult without having internally looking cameras that monitor the pupil.
Possibly, we might want to track the pupil size, but it seems reasonable to assume it is always small, since glare is only an issue in bright light. Although, once the glare is hidden, the pupil would dilate slightly, so it's probably best to use that pupil size in the calculations.
If we wanted to cover the whole retina (not just the fovea), we'd need a much bigger blackspot. Actually, the ideal is not to have a sharply delineated spot, but a gradient, corresponding to the sensitivity of retina that it falls upon.
The first sheet is polarized at 0 degrees and the second sheet is polarized at 90. When both sheets are on the window is black. When you draw a certain tiled pattern on the two sheets though, I hypothesize that you can mostly block the sun from any angle and let most of the ambient light in.
The only way I know how to solve this problem is w/ evolutionary algorithms, which might be well suited. I think someone here might have some mathematical insight into this though, so I'm putting it out there.
-- update --
OK so we need four sheets of LCDs, with each of the window layers having 2 LCD sheets each. Any light that goes through either layer is filtered with some pattern of 0' or 90' pixels.
Any random pattern, as long as the two layers have inverted pixels, will block the sun completely. Ambient light is allowed in at 50% brightness. So there you go.
There's nothing magical about sunlight that will enable you to block it while letting in other light from the same direction. And light from the sun could reach the window at a wide range of different directions.
(If you somehow contrive to have the sun always in the same direction -- say you're in a spaceship and it keeps a consistent orientation relative to the sun -- then this kind of thing could work. Not so feasible here on earth, though.)
*SUN*
--++--++--++--++-- layer 2
layer 1 polarizes all light in the '+' direction or the '-' direction. layer 2 does the same, but is the inverse of layer 1.
Notice that ambient light can pass through at an angle because the light didn't pass through both polarization directions. I think jws is saying 25% of ambient light passes through because the polarization step takes 50%, but half the ambient directions are blocked off completely (say by the moire patterns) so that makes 25% of ambient light.
when you look outside the window, any sunlight that enters your eyes from the angle of the sun is the sun because the sun is so far away. this is why we have well defined shadows.
any light that comes at an angle is all the light that did not come directly from the sun. light coming at an angle is directly aimed at your pupils if you're looking at the source.
what you said, the only way it's true, is if you're always looking directly at the sun.
So do these conceptual glasses have a way to find the direction of the sun, and adjust the moire patterns in real time? Based on the description, it sounded like it would always block rays normal to the plane of the lens, while allowing rays to pass through at any other angle. Rays from the sun will only rarely be normal to the lens, and so they will only rarely be blocked, without an active adjustment to change the "rejection angle." Short of that, I don't follow how the glasses can "tell" sunlight from ambient light, and I don't think it can be done without active logic.
Of course you would have to be very careful on the design, since a failure would be very hazardous.
The UV and infrared are always filtered (by the glass), and the LCD handles darkening the visible light.
I've thought about this also. The increasingly bright headlights are probably counterproductive in a public safety, tragedy-of-the-commons sense. Your bright lights help you see a little better, but other drivers can see worse, because of your lights.
It shouldn't allow more than a small percentage of the windshield to be black, if power is cut it should un-blacken the entire windshield, etc.
One pebble in the windshield at highway speeds, and much of your visibility could go.
My only devil's advocate point would be that drive-by-wire cars typically have mechanical failsafes that the average person is fairly comforted by. For example, many drive by wire systems have some springs that set the car to just above idle if the ECU gets confused. I guess the analog for a potentially opaque windshield is sticking your head out the window, though this may not be fast enough if you're on a windy mountain road, driving through construction, etc.
A liquid-crystal-less region at the bottom of the windshield may do the job, and still do all the information-displaying and sun-blocking you need.
Use two disks of polarized film. When the brightness off the mirror spikes, rotate one disk to reduce the amount of light transmitted. Once a sensor notes that the mirror is no longer reflecting someone's too-bright headlights, it would rotate the disk back to maximum light transmission.
The area involved could be pretty small, and most of the view through the window and mirror would be unaffected.
Curvy roads, and lack of light pollution in the sky, combined with probable sleep deprivation doesn't make for a good situation. Even if you stay on your side of the road, who says that other guy coming in your direction is doing as well?
Headlights in your face are not a very good way to keep track of traffic, neither is a complete absence of light where a car should be though. An optimal solution would probably be something that prevented getting blinded by oncoming headlights while still retaining enough visual cue to be able to perceive that a car is headed towards you and to track its position.
I would see it as a thin film applied to the inside of the windscreen, or possibly some type of HUD optics.
Car makers can already track eyes, because the latest research is in tracking blink rates to detect fatigue.
I'd say this tech is feasible just needs the different disciplines brought together to make it work.
You have no size to compare, because the glow is larger than the headlight itself. You have large distances, so your parallax is minimal, and isn't very accurate anyway. It's dark, so on highways you frequently don't have any known references to compare against (like road width or car size). The closest you get is the distance between headlights and occlusion, which is unknown on any random vehicle and on more widely-spaced vehicles.
When you drive in the dark, if there is no ambient lighting, all you can generally see of a car approaching or behind is its lights, and you can definitely judge distance from that. This is noticeable particularly on motorways - it's very hard when you start to drive but becomes quite natural after a time.
They sell aftermarket interior mirrors, but sadly not exterior/side mirrors.
sound of car crashing
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