h a l f b a k e r ycarpe demi
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Nearly all newer LCD monitors are fed with 24-bit color signals, allowing them to create color 2D images that are perfect to the eye.
But what all monitors lack is the extra 8 bits for the alpha channel.
Start with a normal LCD, and remove the backing from it, including the polarizer. Add a black
and white LCD of the same resolution, also without polarizer or backing. The black and white LCD is made to polarize 90 degrees out of phase with the color LCD.
The result is that when both LCDs are on, the image will appear as normal, the monochrome LCD doing the work of the polarizing filter.
This is where the extra 8 bits come in. They control the intensity level of the monochrome dispaly, allowing the image to blend in with the background. When the monochrome LCD dims, less light is polarized, allowing more light from whatever is behind the display to pass through and blend with the image from the color LCD.
One application would be allowing the user to increase the tranparancy to see what is behind the LCD, without having to move their lazy head.
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I know nothing of polarization of light, but can either of these be polarized after you've removed both polarizers? Let alone 90 degrees out from each other. |
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Otherwise, I kinda wish my notebook had this, except that I think I need a backlight about 98% of the time. |
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An LCD polarizes only in one direction, which is invisible. If a second LCD is rotated so that the polarity is opposite (90 degrees), it will appear opaque. |
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Backlighting might be a problem, but if high quality transflective LCDs are used, this is less of a problem. |
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The normal design of RGB LCD would not be suitable for this because even when full "white" they are less than 30% transmissive. |
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This might be workable with a CMY display (which has three layers that are cyan or clear, magenta or clear, and yellow or clear), though I've not seen such things used outside projection applications. If the technologies can be made thin enough to allow CMY displays to be used for direct viewing, then it should be possible to add a 'milky white' LCD behind it for some neat effects. |
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BTW, one place I've thought of where this might be useful would be in an SLR digital camera eyepiece viewfinder. Depending upon what the user was doing, the viewfinder could either show the picture through the lens, a digital picture, or some combination thereof. For normal use, the camera would mostly show the viewfinder as-is, but with a few readouts (shots remaining, etc.) as well as framing indicators for different print sizes. But when checking exposure settings etc. it could switch instantly to show the digital display. |
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