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I'm confused (and an electricity layman, so please excuse), but why would that power requirement of NFC matter in conjunction with the eInk power usage? Why can

by jjice 3y ago

I'm confused (and an electricity layman, so please excuse), but why would that power requirement of NFC matter in conjunction with the eInk power usage? Why can't the NFC reader be isolated from the display's power usage?

hamandcheese 3y ago
GP said: "I wonder if these thingies can be powered by NFC sensor."
lambda 3y ago
The original poster in the thread was suggesting that if power usage were low enough, it could be powered by the power provided by the NFC in the phone; where the phone provides power for an NFC circuit that is entirely unpowered. If you could power an eink display that way, you could have a completely unpowered frame, which you could set via NFC. So yes, of course NFC can be isolated from the displays power usage, the originator of this thread was just suggesting it would be neat if you could power it via NFC. But NFC doesn't provide nearly enough power, nor likely enough bandwidth to do that in a reasonable amount of time.
- rtkwe 3y ago
  In theory you could maybe charge a supercapacitor over time with the power from NFC and then perform the update but you're looking at at least 15x (50mW vs 750mW average update draw) the update time standing there holding the phone to the display while you trickle power over that connection. In reality with losses and extra draws to manage the screen you might not break net positive on the energy from the phone or you'd be looking at a 30-50x multiple instead of /just/ 15x.
rtkwe 3y ago
Because the person I was replying to specifically asked if you could pair the two and power/update a stand alone display with just NFC delivered power? The devices for updatable price labels based on eInk already exists and I mention it in my post, it's powered by a low self discharge battery. Those IIRC use a special radio fob that connects to your phone instead of using NFC but you could probably do a largely drop in replacement for the radio circuit with NFC but that still doesn't solve the issue of updating the eInk screen. That's an order of magnitude more power required.
- anigbrowl 3y ago
  YEs, but their description of what they were imagining made clear they were using the word 'powered' to mean 'controlled by', not in the literal sense of delivering electrical power. I blame advertising for this, 'powered by [software product]' has become ubiquitous and exploits the relatively low literacy level of the public.
  - rtkwe 3y ago
    I really think they actually meant literally powered by here. Being on HN I make the presumption that commenters are a bit more savvy than the average Joe Public. https://news.ycombinator.com/item?id=38002621 https://news.ycombinator.com/item?id=38002621
    - anigbrowl 3y ago
      "Hang frame on the wall, choose the image in the app, bring phone close to frame, boom, the frame has new image." It's extremely obvious the person you replied to was talking about controlling the tablet, not supplying electricity to it. Their subsequent remarks are beside the point, this is what led to the confusion in this thread.
      - rtkwe 3y ago
        Beside the point? It's pretty on point if you're trying to say they weren't talking about powering the device too... Also there are only two people here confused about GP's meaning. Can it be controlled by NFC is a trivial question.

by jjice 3y ago

hamandcheese 3y ago

GP said: "I wonder if these thingies can be powered by NFC sensor."

lambda 3y ago

The original poster in the thread was suggesting that if power usage were low enough, it could be powered by the power provided by the NFC in the phone; where the phone provides power for an NFC circuit that is entirely unpowered. If you could power an eink display that way, you could have a completely unpowered frame, which you could set via NFC. So yes, of course NFC can be isolated from the displays power usage, the originator of this thread was just suggesting it would be neat if you could power it via NFC. But NFC doesn't provide nearly enough power, nor likely enough bandwidth to do that in a reasonable amount of time.

rtkwe 3y ago
In theory you could maybe charge a supercapacitor over time with the power from NFC and then perform the update but you're looking at at least 15x (50mW vs 750mW average update draw) the update time standing there holding the phone to the display while you trickle power over that connection. In reality with losses and extra draws to manage the screen you might not break net positive on the energy from the phone or you'd be looking at a 30-50x multiple instead of /just/ 15x.

rtkwe 3y ago

Because the person I was replying to specifically asked if you could pair the two and power/update a stand alone display with just NFC delivered power? The devices for updatable price labels based on eInk already exists and I mention it in my post, it's powered by a low self discharge battery. Those IIRC use a special radio fob that connects to your phone instead of using NFC but you could probably do a largely drop in replacement for the radio circuit with NFC but that still doesn't solve the issue of updating the eInk screen. That's an order of magnitude more power required.

anigbrowl 3y ago
YEs, but their description of what they were imagining made clear they were using the word 'powered' to mean 'controlled by', not in the literal sense of delivering electrical power. I blame advertising for this, 'powered by [software product]' has become ubiquitous and exploits the relatively low literacy level of the public.
- rtkwe 3y ago
  I really think they actually meant literally powered by here. Being on HN I make the presumption that commenters are a bit more savvy than the average Joe Public. https://news.ycombinator.com/item?id=38002621 https://news.ycombinator.com/item?id=38002621
  - anigbrowl 3y ago
    "Hang frame on the wall, choose the image in the app, bring phone close to frame, boom, the frame has new image." It's extremely obvious the person you replied to was talking about controlling the tablet, not supplying electricity to it. Their subsequent remarks are beside the point, this is what led to the confusion in this thread.
    - rtkwe 3y ago
      Beside the point? It's pretty on point if you're trying to say they weren't talking about powering the device too... Also there are only two people here confused about GP's meaning. Can it be controlled by NFC is a trivial question.