Is there such a thing as LCD window curtains?

• Is there such a thing as LCD window curtains?
  Posted by Artlav on 18 Sep, 2015 14:23
• Not the BTTF2 kind, no.
  
  I was thinking about a window-sized single pixel LCD display, essentially, glued on top of the window's glass.
  Unpowered it's transparent.
  With power it's opaque, with no sunlight getting through.
  
  Was something like that done before?
  I remember thinking about it a couple of decades ago, and writing it off as something ludicrously expensive the Bill Gates' "smart home" might have.
  But these days window-sized LCD screens are almost dirt cheap, and a single pixel thing like that should be even cheaper.
  
  So, why not?
  If no why, then where can i find one or how can i make one?
  That is, should i waste a good spare laptop screen experimenting, or can i just go shopping?
• #1 Reply
  Posted by Balaur on 18 Sep, 2015 15:32
• Yes, it's called switchable glass or switchable window tint. Or some proprietary name.
• #2 Reply
  Posted by tom66 on 18 Sep, 2015 15:59
• #3 Reply
  Posted by G7PSK on 18 Sep, 2015 17:23
• I think it's used on the space station, certainly back in the early 90's when I purchased my first auto welding helmet the Racal sales man said it was. I do remember that back the the thing cost nearly a thousand pounds, £450 for the helmet and over £500 for the filter and blower unit on a belt that ensured the user did not breath welding fumes.
• #4 Reply
  Posted by GreyWoolfe on 18 Sep, 2015 19:22
• http://www.glass-apps.com/products/smart-glass-windows/?gclid=CjwKEAjw7O6vBRDpi7O-8OWSkwESJACNFsgxApqgvroOzWiVXYHkFTW27CGkCyqCx6r3jDZ4OHqb4RoC-abw_wcB
  
  They also make a film that goes on the glass.
• #5 Reply
  Posted by KermitDK on 18 Sep, 2015 19:31
• Are you thinking of something like this ? :
  
  
• #6 Reply
  Posted by Red Squirrel on 18 Sep, 2015 23:26
• Saw something like that on one of Mike Holmes' shows, they used it for a shower glass, it was pretty neat.
• #7 Reply
  Posted by AF6LJ on 18 Sep, 2015 23:29
• As I understand it the sun solarizes the the LCD panels which makes them less able to provide a decent shade. I've seen this in amateur radio gear that use LCD displays they loose the ability to generate a high contrast ratio.
• #8 Reply
  Posted by Psi on 19 Sep, 2015 03:12
• Yep, you can get it installed in your house, it just cost so much you wouldn't want to
  
  I've seen it being installed in a house on one of those home building TV shows
• #9 Reply
  Posted by Chris C on 19 Sep, 2015 03:51
• The high cost was no surprise.  What surprised me was energy consumption, 12W per square meter on the one I looked up.  I'd expected it to operate like a capacitor.
• #10 Reply
  Posted by Psi on 19 Sep, 2015 03:58
• I'd like to build a large 28" stand like in the first video on this page, then have a data projector at the rear to replace my desktop computer monitor. It would look awesome
  
  http://www.glass-apps.com/products/smart-glass-windows/?gclid=CjwKEAjw7O6vBRDpi7O-8OWSkwESJACNFsgxApqgvroOzWiVXYHkFTW27CGkCyqCx6r3jDZ4OHqb4RoC-abw_wcB
• #11 Reply
  Posted by SeanB on 19 Sep, 2015 06:45
• It is a LCD, so will be a big capacitor operating at around 32Hz, so yes it will draw a bit of power to charge it to alternate voltages. ITO coatings in contact with the cholesterol in a standard LCD display will corrode with applied DC, so they need AC drive ( and it has to be an exact 50% duty cycle for long display life, otherwise there is a DC component to the drive which will kill the display with time) and this does use power, both in losses in the film resistance and in the dielectric absorption of the cholesterol used.
  
• #12 Reply
  Posted by Chris C on 19 Sep, 2015 10:58
• Quote from: SeanB on 19 Sep, 2015 06:45

  ITO coatings in contact with the cholesterol in a standard LCD display will corrode with applied DC, so they need AC drive

  
  I never knew that, thanks.  Now the power consumption makes sense.