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E-ink Really??

A project log for CL-32

A mobile dev terminal/hacker device/anything you like!!

mooseprmoosepr 08/21/2024 at 15:224 Comments

I wanted to stick to the retro asthetic, so the screen being up the top left corner feels right. I considered a few options, but kept circling back round to e-ink.

Colour LCD

There are lots of really great little IPS screens with really impressive pixel densities, but they are generally designed for smart watches and the like, so they are super tiny (see TinyPi Pro ;) )

Monochrome LCD

I did try and hunt for some dot matrix lcd screens to really nail the retro aesthetic, but they seemed to be low resolution and pretty expensive. Also they can be a bit tricky with viewing angles and hard to see in low light

E-ink

So e-ink was the next on the hit list. I really love the way it looks, literally like printed paper, but the refresh rates are shocking. For displays with any colour on them, it can be up to 15 seconds to refresh the screen with lots of flashing, not really something that works well with a keyboard in a code editing situation. After some research, I found that the plain black and white screens could fully refresh much faster, and there was the option of fast or partial update which might make it usable...

The Curveball..

I had in my box of bits a Sharp Memory display, its a low power lcd that has a bit more of a reflective nature to it, and so has a bit more readability when the light isnt great. I hacked one onto my test boards so that i could compare and contrast

At first, things look nice!! (disregard that blob of damage on the screen) there are more pixels, and the refresh is instant, but it soon started to loose its shine. Firstly the extra pixels means that you have to use larger font to keep the same level of readability. While this is not the end of the world, it does kill off the advantage gained by the higher resolution. Also as i was moving the boards about, i noticed shocking contrast when your not looking directly at the device

Compared to the crisp e-ink, this was pretty bad. Coupled with the fact that i need 5v to get the screen to work, and the poor old Sharp Memory display went back into the parts bin

Discussions

Gravis wrote 09/02/2024 at 20:44 point

I think e-paper displays are awesome. I also think they are WAAAAY overpriced and I'll be interested in them when the patents start expiring and we have a second producer of e-paper displays.

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moosepr wrote 09/03/2024 at 08:48 point

Yeah its the screen is the biggest chunk of the costs. in the region of $10 for these 2.9" screens.

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JimJJewett wrote 09/02/2024 at 15:41 point

There are people who prefer the dark, and others who prefer it for security reasons.  I do agree that these are bad preferences in an educational example, but it might be a tolerable compromise.

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moosepr wrote 09/02/2024 at 16:13 point

I struggled as soon as I saw them side by side, the sharp display just looked so grey and muddy compared to the e-ink

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