I’m designing an electronic product that displays black text on a solid-white background. It’s like a digital whiteboard that mimics the look of a real whiteboard, so that black text would change and update on a solid-white background. It’s a small-sized product that stands on the kitchen counter.
It’s a high-quality product, and the surface needs a high-quality white finish, which is constantly displayed as white. Ideally it would look like a plastic surface that can somehow display type. I’m not sure how to create that look.
I first thought of using an LCD display, where the white background is created from white pixels. This would always need to be on though, and I think it would require too much energy. I also thought of using a thin material and projecting the type through the back of the surface. I’m not sure if that could achieve the correct look. I’m looking for a similar product. Any ideas?
Kindles use e-ink displays. E-ink is great for high contrast and persistent display with low power. But it has it’s own set of tradeoffs…limited grayscale depth, slow refresh rate, etc. I would check one out and see if it is what you want.
Projecting through the material is possible but only if you do something similar to the Nike Fuel band, where you have a large array of LED’s that can shine through the material. That will not yield black text however and will be very expensive and much lower resolution.
E ink does not “light” anything. It’s why they usually call it e-paper. There is no backlight - this gives it excellent readability in bright light which is why people love them for using their e-readers at the beach, when normal LCD’s are useless. On E-paper, pixels are simply “Switched” - once they are set to either black or white, they remain that way with zero power consumption making it extremely power friendly. This is also what they use on the Pebble smart watch to achieve the ultra low power consumption.
This means however that it will not work in the dark without some external form of illumination. Now a whiteboard is not an illuminated surface, so maybe that is fine.
LED’s will draw a huge amount of power. Which is why on the fuel band they are off 99% of the time and the array is very small. Yes, they are molded into the silicone material. Molding into hard plastic would likely not be feasible, I would expect the shrink and stress of the rigid material to damage the circuits - you would likely have to mold the hard plastic then assemble something from behind.
I see. In photographs, the standard Kindle (without illumination) looks more grey than paper-white. Do you know if pixels can be as white as paper, without illumination?
Paper is made “white” through the use of chemicals called optical brighteners. These chemicals take the paper (which is naturally yellowish) and cause it to reflect more blue light causing it to appear bright white.
Those chemicals are naturally unstable which is why white paper over time turns back to being yellow. It’s not the paper “Aging” it’s the optical brighteners wearing out.
Beyond that you’re left with a typical LCD display.