An e-ink display needs power only to change the picture – not to keep showing it. Combined with a frame that spends most of its time in deep sleep, that is why MelonFrame can run for months on one charge.
Power is only needed to change the picture
An LCD screen has to be powered every second it shows something: the backlight is on, and every pixel is actively held in place. Switch it off and the picture is gone.
E-ink – including E Ink Spectra™ 6, the display used in MelonFrame – is bistable. When the image changes, a short series of voltage pulses moves charged colour pigments inside each pixel to the front. Once they are in place, nothing more is needed – the pigments stay put, and the picture remains visible without powering the display. On MelonFrame this takes about 20–30 seconds, and the screen flashes while it happens: the pigments are being reset and rearranged.
Deep sleep: very little power
The display itself needs no power to hold the picture, but the frame's electronics – the small computer inside, its clock and its Wi-Fi – still need a tiny amount. Between image changes, MelonFrame goes into deep sleep: Wi-Fi is off and the power draw drops to the microamp range, thousands of times less than when it is awake. It wakes on its own at the times set in its schedule, changes the picture and goes back to sleep.
Because the frame is asleep most of the time, it can't be reached from the app straight away. To send new pictures or change settings, wake it first: press the wake button on the back, or double-tap the front of the frame. It then stays awake long enough for the app to connect.
What that means in numbers
A common LCD photo frame uses around 5 watts while it is on. Left on all day, that adds up to roughly 30–45 kWh a year – about as much as a fridge uses in a month or two.
MelonFrame has a 4000 mAh battery (about 14.8 Wh) that lasts up to six months, depending on how often the image changes. Over a year that is in the range of 30 Wh – around a thousand times less energy than an always-on LCD frame. In practice, that means no cable on the wall and one charge every few months.
Less power, fewer compromises
- No cable: hang it where there is no socket.
- No glow: it doesn't light up the room at night.
- Calm by design: a picture that changes when you want – not a screen that is always "on".
Read next: E-ink vs LCD digital frames: what's the difference?
