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posted by janrinok on Thursday March 19 2020, @07:39PM   Printer-friendly
from the almost-magic dept.

7.5-inch e-ink display is powered completely by NFC:

NFC (Near Field Communication) is usually only used to for quick text transfers, like a tap-and-pay transaction at a register or a quick data transfer from an NFC sticker. A company called "Waveshare" is really pushing the limits of NFC, though, with a 7.5-inch e-ink display that gets its data, and its power, from an NFC transfer. The $70 display doesn't have a battery and doesn't need a wired power connection.

E-paper (or e-ink) displays have the unique property of not needing power to maintain an image. Once a charge blasts across the display and correctly aligns pixels full of black and white balls, everything will stay where it is when the power turns off, so the image will stick around. You might not have thought about it before, but in addition to data, NFC comes with a tiny wireless power transfer. This display is designed so that NFC provides just enough power to refresh the display during a data transfer, and the e-ink display will hold onto the image afterward.

NFC's power transfer works just like wireless phone charging: the reader (probably your phone) generates an RF field to transfer power to the passive NFC object. NFC stickers (and any other NFC device) have a sizable spiral antenna to harvest the RF signal, just like a wireless charging coil. The amount of power you can transfer over NFC depends on the design of the object and the reader, but Waveshare warns that some phones might not put out enough power. If your phone doesn't work, the company recommends an NFC board that puts out 1.4 watts of power, but Waveshare also shows the device working with a pretty old Android phone, a Samsung Galaxy S7 Edge from 2016.


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  • (Score: 2) by Hyperturtle on Friday March 20 2020, @01:13PM

    by Hyperturtle (2824) on Friday March 20 2020, @01:13PM (#973463)

    I agree, these are more static, although usually easy to read.

    These might be good for smaller displays that have things like compass direction, temperature sensor readings, "check engine light" details, etc.

    They could be a complimentary display component to keep the main "good" screen from being too cluttered with occasional or infrequently changing data.

    I myself have been looking at these for various small projects, and the utility of them is not for anything that sees changes that require a refresh or update within a few seconds. A virtual flip-clock, for example -- or to act as the screen for a home thermometer hub where you can add a zillion sensors to an arduino or raspberry pi cheapo device deployment in the home, and get transmissions to a central device that can then display room or zoning temps.

    (or just buy an oregon scientific hub and its inexpensive units for strategic placement around the house...)

    Lots of people are disappointed with these screens, and some of the forum comments elsewhere belie that fact--people can't see past how their cell phone screen works -- but in the right location they can be pretty neat or too advertisy. Consider dynamic menus on tables at restaurants, prices for things in stores and replacing some signage, or those places that have shopping cart screens that show ads as you shop... or elevator panels that show ads as you are trapped... or gas station pump screens showing ads for their private brand card or junk food that you can't avoid without getting back into your car... or whatever wherever screens that abusively show us ads no matter where we go and what we do? These are cheaper than the existing color flatpanels often in use now that frequently don't change much more than just showing a number of slides on a carousel rotation...)

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