I've owned a Casio G-Shock that was negative by default (G-5600KG) and I found that the viewing angle on a negative display was much more narrow than on a positive. Most of the reviews on Amazon state the same. Anyone have an explanation for this?
How to Convert a Digital Watch to a Negative Display
21–30 of 51 posts
Re: How to Convert a Digital Watch to a Negative Display
#22Nice. I remember doing this to my scientific calculator at school. Modern colour LCDs are still polarised, so I can only view my phone and tablet in one orientation when wearing my polarised sunglasses. On the plus side, they make for an excellent real life ad-block to those annoying video billboards (which are just portrait LCD TVs). I wonder how practical it would be to make a private display by removing the polari…
> I wonder how practical it would be to make a private display by removing the polarising film from it and then viewing with polarised glasses.
It's been done, pretty much how you'd expect:
http://www.instructables.com/id/Privacy-monitor-made-from-an...
Re: How to Convert a Digital Watch to a Negative Display
#23Inkjet transparency sheets like you'd find at your local office supply store [0] are polarized; you may not have to order polarizing film. I used to own a car that had an LCD display where the orientation of the polarization was perfectly set so if I was wearing my polarized sunglasses, the screen was blank. I cut out a little overlay made out of an overhead transparency and fixed the problem. 0: http://www.officemax…
An overlay of other polarizing material won't change the polarization unless your transparencies are somehow quarter wave plates? (http://en.wikipedia.org/wiki/Circular_polarizer#Circular_pol...)
Re: How to Convert a Digital Watch to a Negative Display
#24Inkjet transparency sheets like you'd find at your local office supply store [0] are polarized; you may not have to order polarizing film. I used to own a car that had an LCD display where the orientation of the polarization was perfectly set so if I was wearing my polarized sunglasses, the screen was blank. I cut out a little overlay made out of an overhead transparency and fixed the problem. 0: http://www.officemax…
An overlay of other polarizing material won't change the polarization unless your transparencies are somehow quarter wave plates? ( http://en.wikipedia.org/wiki/Circular_polarizer#Circular_pol... )
Using a linear polarizer does change the polarization. If he puts his polarizer halfway between the incident angle and the desired angle, he'll get cos⁴(theta/2) of the original intensity in the desired polarization.
Re: How to Convert a Digital Watch to a Negative Display
#25Inkjet transparency sheets like you'd find at your local office supply store [0] are polarized; you may not have to order polarizing film. I used to own a car that had an LCD display where the orientation of the polarization was perfectly set so if I was wearing my polarized sunglasses, the screen was blank. I cut out a little overlay made out of an overhead transparency and fixed the problem. 0: http://www.officemax…
An overlay of other polarizing material won't change the polarization unless your transparencies are somehow quarter wave plates? ( http://en.wikipedia.org/wiki/Circular_polarizer#Circular_pol... )
If you have two perpendicular polarizers, no light will pass through both. But, if you insert a polarizer at a 45 degree angle to both of them inbetween, some light will pass through. Am I wrong?
Re: How to Convert a Digital Watch to a Negative Display
#26I did this a lot to LCD gaming handhelds back in the early 90s. Also using two polarising sheets to understand polarisation. Was very interesting, a pity nowadays taking apart stuff is not so easy.
Re: How to Convert a Digital Watch to a Negative Display
#27Nice. I remember doing this to my scientific calculator at school. Modern colour LCDs are still polarised, so I can only view my phone and tablet in one orientation when wearing my polarised sunglasses. On the plus side, they make for an excellent real life ad-block to those annoying video billboards (which are just portrait LCD TVs). I wonder how practical it would be to make a private display by removing the polari…
> I wonder how practical it would be to make a private display by removing the polarising film from it and then viewing with polarised glasses. It's been done, pretty much how you'd expect: http://www.instructables.com/id/Privacy-monitor-made-from-an...
There are quite a few hacks around but I wondered if there was some reason these aren't more widespread or commercially available. Business idea?
You could also make something that filters all light but near infra-red so it could be seen by CCDs (on cameras or phones) but not with the human eye. Or do the reverse and flood the picture with near infra-red to prevent it being photographed.
Re: How to Convert a Digital Watch to a Negative Display
#28Inkjet transparency sheets like you'd find at your local office supply store [0] are polarized; you may not have to order polarizing film. I used to own a car that had an LCD display where the orientation of the polarization was perfectly set so if I was wearing my polarized sunglasses, the screen was blank. I cut out a little overlay made out of an overhead transparency and fixed the problem. 0: http://www.officemax…
An overlay of other polarizing material won't change the polarization unless your transparencies are somehow quarter wave plates? ( http://en.wikipedia.org/wiki/Circular_polarizer#Circular_pol... )
Most thin sheets of polyester actually function as retarders (not necessarily quarter wave plates) due to the way their molecules are aligned during manufacturing. Here's one of the better cites on the topic, it includes some math to design any desired retarder:
Re: How to Convert a Digital Watch to a Negative Display
#29Related to the Polarization subject, when you are shopping for Polarized sunglasses, then take two copies of the sunglasses and placed them so that you are looking through both lenses, but one in 90 degree and notice if it turns opaque-black.
Many times in the past when I was looking for some cheap polarized sunglasses, I found that some were actually falsely labeled.
Re: How to Convert a Digital Watch to a Negative Display
#30Earlier quoted context omitted.
> I wonder how practical it would be to make a private display by removing the polarising film from it and then viewing with polarised glasses. It's been done, pretty much how you'd expect: http://www.instructables.com/id/Privacy-monitor-made-from-an...
There are quite a few hacks around but I wondered if there was some reason these aren't more widespread or commercially available. Business idea? You could also make something that filters all light but near infra-red so it could be seen by CCDs (on cameras or phones) but not with the human eye. Or do the reverse and flood the picture with near infra-red to prevent it being photographed.
I think you can buy this kind of thing, I've seen them in use in some offices where sensitive information is being viewed.