Secondly, there is the e-paper display, which you can choose in different sizes: 1.54, 2.13, 2.9, and up to 7.5 inches. You can also choose between monochromatic displays or versions with up to 6 colors.
In my case, I acquired the 7.3″ Spectra™ 6 E-Ink display, which supports up to 6 colors: White, Black, Yellow, Red, Green, and Blue. As with other Seeed Studio terminals, it can be configured using their SenseCraft web application if you prefer not to program and want something ready to go quickly. I won’t go into detail about that, as there is plenty of information online and it is quite intuitive. However, I prefer the DIY approach, so I started developing something from scratch.
First of all, these types of color displays have a much slower full-screen refresh rate compared to monochromatic ones. This may seem obvious, as the canvas must be refreshed for each color independently. This is because the E-Ink Spectra 6 / ACeP terminal contains microcapsules with several color pigments inside. Depending on the voltage applied to each pixel, a specific colored fluid is moved toward the visible surface so we can see it, while the other colors for that pixel remain hidden.
GIF from: https://www.eink.com/tech/detail/How_it_works
Since the color is physically formed within each pixel, refreshing all pixels takes time. It is important to highlight this for your implementations: you won’t be able to create content that requires frequent updates. A full refresh takes between 20 and 30 seconds, during which the screen flashes intensely as the pigments are rearranged. This rules it out for clocks with second hands or real-time notifications, but makes it the ideal candidate for static dashboards, signage, or low-power digital art.
As you can see, I have drawn five suns at the top using the display’s native pure colors, and at the bottom, the colors resulting from mixing them. Even when drawing suns, the colors remain very effective. In this way, we have managed to achieve illusory colors for: