Electrochromic Visor Aids Motorcyclists

opticsorg writes "A team from Uppsala University and the firm Chromogenics Sweden AB have developed a flexible electrochromic foil and integrated it into the visor of a motorcycle helmet. The result is a visor that the rider can electronically switch between dark and transparent states. Applying a voltage of about 1V to the initially transparent visor causes it to darken in a matter of seconds. When the voltage is turned off, the visor keeps its properties, while applying a reverse voltage makes it revert to its natural lightly tinted state."

Comments

MIT and LCDs

[Mr. Darl McBride]

Something similar was tried as a studen project at MIT. They used a flexible LCD panel, fixed over the faceplate of a motorcycle helmet. It had the desired effect, letting them dim the view during the day and lighten it at night, all with just three AA batteries, a rocker switch, and a simple 555 strobing timer circuit.

The project lead didn't manage to show up for the project class presentation however; he'd wiped out on the way to school.

Apparently on a colder morning, the LCD began to dim on its own as the cold wind affected the crystals, making them darken slowly and subtly. By the time he consciously realized he wasn't seeing well, he'd already skidded into the back of a flatbed truck!

I guess the simple lessons can be painful ones at MIT.

This isn't "transparent"

[wowbagger]

The maximum transmissivity is 50% - in other words, at its "light" setting, it STILL blocks half the light coming in.

At its "dark" setting, it transmits 20%.

So what you have is not "clear" and "krylon black", but rather "dark" and "darker". While this is useful, it still would be darker than clear.

And for all the people who will post about "I want this on my car" - no, you don't. Many municipalities have a legal limit of about 90% on car windows - pass less than this and the nice police officer can ticket you. Since 50% < 90%, if the cop wants to give you grief he can.

Re:This isn't "transparent"

[Shiifty]

50% still isn't good enough for night time riding. I use a tinted visor on my helmet and sometimes get caught out after dark without my clear visor. The tint isn't too dark, maybe 35% but its enough to make you feel uncomfortable on main streets, nevermind rural areas. 50% wouldn't be much better. Simple solution, just flip it up if you get caught out, thats what I do.