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E-paper display reaches the realm of LCD screens

Original Article

Hacker News Discussion

This discussion revolves around a new e-paper display technology capable of refreshing at 75Hz, sparking robust debate about its practicality, power consumption, and potential applications compared to existing display technologies like LCD and OLED.

Power Consumption and the Trade-off for Refresh Rate

A central theme is the concern over power draw, especially given e-ink's reputation for low power consumption on static content. Users debate whether the increased refresh rate negates e-ink's battery advantage.

  • "FPGA and e-ink at 75Hz? It sounds like it will have a high power draw." - efitz
  • "If your phone screen became a 75hz e-ink display I'm pretty sure that would actually drain your battery faster than currently, which I assume is once per day. Would you accept that compromise of going from weeks to <1 day?" - dankwizard
  • "EInk needs a lot of power to move the heavier ink particles around. If you are doing that more and more rapidly, then even more power is drawn. By 75Hz, I'm almost certain that LCD is far more power efficient. The LCD pixel (aka the liquid crystal) is a glorified capacitor, it takes some power to charge but it's exceptionally 'light' compared to eink." - dragontamer
  • "EInks advantage is that if you turn off power, the ink stays put. So you spend a ton of power moving the ink around and then save lots and lots of power over the next seconds, minutes or more." - dragontamer
  • "Our driver board, under continuous use, draws about 1 to 1.5W." - alex-a-soto
  • "E-ink screens are quite power hungry when it comes to peak current. Modern high-resolution panels can consume >20 W peak." - dragontamer

However, some argue that battery life is less of a concern for them if it means a better user experience, and that the technology's efficiency depends on how much of the screen actually updates.

  • "I use E-ink for the reduced eye strain, the battery draw really does not bother me. I like having devices that last weeks on a single charge, but I would gladly charge them more often for an increased refresh rate." - dotancohen
  • "But I would gladly charge them more often for an increased refresh rate." - dotancohen
  • "I'm curious too. But I would definitely take the risk and purchase such a device, so long as it comes with an EMR stylus." - dotancohen
  • "Just an anecdote, but my phone ran out of battery most often when a full charge lasted almost two days. It made me lazy about charging at night. Now I have a wireless charger next to my work computer and in my car, I probably don't need to charge at night any more. Granted, I'd prefer a large battery when I'm traveling, but battery size is less important to me recently." - 8organicbits
  • "Yoric: Out of curiosity, if you have 75Hz but you're refreshing sparingly (e.g. you're in VSCode writing, unless you're scrolling, most pixels remain unchanged), wouldn't e-ink remain power-efficient?"
  • "McNulty2: Don't want 75Hz or even 10Hz from my Epaper. Want a maximum battery life, 1Hz is plenty"

E-Ink's Refresh Rate Optimization and Partial Updates

The discussion delves into how e-ink achieves higher refresh rates, with a focus on the role of partial screen updates and the efficiency gained when only a portion of the display changes.

  • "I think a large part of it is because modos is really good at partial screen updates. This is also, in my understanding, how they achieve the high FPS rate." - amarant
  • "The parts of the screen that doesn't update, courtesy of being e-ink, don't use any power at all. LCD will use power if you're looking at a static image, eink won't. And a lot of the time, 95% of the screen is a static image and only 5 percent actually updates. One of Modos' biggest innovations is successfully taking advantage of that." - amarant
  • "So it's not actually 75hz all the time then? Depending on what's on the screen? That's unfortunate. I'm imagining a fast scrolling game with complex backgrounds where most of the pixels are changing values every frame, I assume it completely breaks down in that case." - ranger_danger
  • "It's 75hz when it needs to be, but if 2 frames are mostly identical, it doesn't needlessly move ink around. Effect: 75hz always as far as the user is concerned, but sometimes it uses less power than that when possible, due to very clever optimisations at the firmware level. Or that's how I understand it anyway." - amarant
  • "dredmorbius: Probably. E-ink drivers ("waveforms" is, I believe, the term of art) frequently target refreshes only at the portion of the display that has updated, using rectangles or other more-specific geometries to limit that area."
  • "For text updates, where there's literally a cursor which moves at typing speeds, update frequency is quite low. Where you're updating or paging through documents, paginated navigation (where the whole screen refreshes at once, then remains unchanged for several seconds to minutes or longer) is quite efficient." - dredmorbius
  • "mcdonje: Are LCD screens driven on a pixel by pixel basis, or is the entire screen driven on each refresh? Because the article says they're only causing changed pixels to refresh. If so, you're probably still right when it comes to watching a video or something, but e-ink could be more efficient for drawing, writing, or reading."
  • "ahartmetz: It seems much more practical (if a little less power-efficient) to implement the no diff -> no refresh logic for screen regions in the display hardware. The RAM and logic for a display-side framebuffer can't be expensive today, a couple of Euros for the extra board space and chip(s). If that stuff takes off, just additional transistors in the all-in-one ASIC. For the whole screen, that more or less already exists in laptop hardware: "panel self-refresh". HDMI and DiplayPort might need a new extension or something? Is there anything?"
  • "wtallis: The Embedded DisplayPort standard has had the panel self-refresh feature since 2011, and the partial update feature since ~2015. I found a press release from Parade in early 2017 for a TCON supporting the partial refresh feature. I don't think there's anything missing from the ecosystem other than a strong impetus to use those features."

Ghosting, Contrast, and Color Reproduction

Users express concerns about the practical limitations of e-ink displays, such as ghosting, contrast levels, and color fidelity, particularly at higher refresh rates or in specific modes like dark mode.

  • "Would love to see the performance trade-offs. I don't mind more battery draw, but how many shades of grey does it support? How bad is the ghosting? How white is the background? Is it clear enough to be used white-on-black? How often does it need a full screen refresh?" - dotancohen
  • "Really? My Nook and Boox devices aren't. The ghosting in even the highest quality refresh mode is just to much in 'dark mode'. I'd love to see this." - dotancohen
  • "numbsafari: Clearly there are some issues with ghosting?"
  • "anecdatas: The ghosting in that video is unbelievably strong. To the degree that I'd consider that unplayable. It's certainly not the experience the dev intended (given how much effort they put into the moire shader). Is refresh rate necessarily tied to ghosting? Like higher refresh rate also means higher ghosting?"
  • "pedrogpimenta: This is great, but I see lots of ghosting and apparently low contrast. Sad to see no mention of it in the article."
  • "hn92726819: Be warned: each layer of eink reduces contrast. With 4 layers, the contrast of the color boox tablet is terrible. Also, if you buy from boox, you have to pay about $50 to return it. Not worth it at all in my experience, unless you will always be in direct sunlight."
  • "diabllicseagull: I suppose if we are at comparable refresh rates to LCDs, next metric to compare against is response time? I see significant amount of trailing while scrolling."
  • "teucris: Response time is on par with LCDs - the trailing you’re seeing is ghosting, which in most situations is not common but does occur occasionally."
  • "mrheosuper: Kind of, many e-ink device when using under sunlight lose their contrast overtime. The Fossil Eink watch is one of the example."
  • "cyberax: I have an e-ink display that's now 15 years old. It's definitely a bit less clean, there is sometimes mild ghosting even after doing a full refresh. Doing two refreshes in quick succession fixes that."

The discussion also touches on the technology's longevity and potential for degradation.

  • "How long do the pixels last before they start getting stuck?" - cheschire
  • "Up to now, E inks advantage is that if you turn off power, the ink stays put. So you spend a ton of power moving the ink around and then save lots and lots of power over the next seconds, minutes or more. That's why EInk is ideal for once-a-day updates... The less you update, the less power used." - dragontamer
  • "This could be actual burn in, or it could be a failure in how they are refreshing (with some potential fix if refreshed properly). I’m not familiar enough to be certain myself, but I personally suspect they are likely being driven too hard and are truly damaged." - Modified3019
  • "smusamashah: Do e-ink screens expire? Like screen slowly loose the ability to move the particles around, or the particles loosing the ability to move with charge. If so, won't high refresh rates degrade eink rapidly."
  • "alex-a-soto: I’d recommend watching the video below, where we talk about how fast refresh affects a panel’s lifespan."

Eye Strain and Readability

A significant portion of the conversation centers on the perceived benefit of e-ink displays for eye comfort, especially in contrast to backlit screens. However, there's skepticism about whether this is a proven advantage or a placebo effect.

  • "I use E-ink for the reduced eye strain, the battery draw really does not bother me." - dotancohen
  • "EInk also displays quite nicely with a "frontlight", which brightens the background (whiter whites) without washing out the foreground (print/ink). Illuminated LCD displays tend to wash out the dark fields, though I've not viewed e-paper directly and cannot speak to that." - dredmorbius
  • "wolrah: E-ink's other advantage is that it reads like paper. In a desktop context I could not possibly care less about the power consumption, but being able to read a forum thread, chat channel, HN discussion, etc. without a backlight would make my eyes very happy."
  • "luqtas: there's no evidence/meta-analysis pointing e-ink screen tiring eyes more/less than LCD."
  • "wolrah: Is there any actual scientific study saying anything either way? I'm aware of a lot of anecdotal evidence in favor of e-ink displays being easier on the eyes than normal LCDs in some way, my own personal experience included, but I will happily admit I'm wrong if there are studies indicating otherwise."
  • "adgjlsfhk1: the e-ink advantage is that it forces screen brightness to track room brightness."
  • "m463: Actually, the advantage is that it is reflective and works better in high ambient light."

The Modos Project and Open Source Philosophy

The Modos project itself, and its commitment to open source development, is met with support and enthusiasm, seen as a way to foster innovation and community involvement in e-paper technology.

  • "The Modos project and its commitment to open source development is met with support and enthusiasm, seen as a way to foster innovation and community involvement in e-paper technology." - (General sentiment from multiple users)
  • "Call me crazy, but I'd rather see these guys get a couple million than yet another chatgpt wrapper." - precompute
  • "alex-a-soto: I agree with your points. I would add: Making the project open allows people to reuse displays they already own. Others can contribute and build on what’s been created. Open source firmware, documentation, and the driver board make development more accessible and help remove barriers that previously slowed community projects. It’s designed to work with a variety of electrophoretic panels, not only those from E Ink. In the long run, this openness will strengthen the ecosystem, making it easier for new ideas to take shape and spread."
  • "chrisMarshallNY: > instead of our secret sauce, we have open sauce I enjoyed that quote. Not really knowledgeable enough about the tech, to comment further, but I like EInk, and look forward to seeing it be more useful. Thanks!"
  • "Cherub0774: I am absolutely not surprised to see his name behind this startup. I've been following his work for years at this point; his YouTube channel has always deeply impressed me, and he's done wonderful open source work in the realm of E-paper for quite some time now. Kudos to him, and I wish him all the best."

Comparison to Other Display Technologies

Throughout the discussion, e-ink's capabilities and limitations are contrasted with those of LCD, OLED, and older reflective technologies like Memory LCDs and MIP displays, highlighting the specific niches and trade-offs of each.

  • "LCDs can have superior power draw than EInk. See the microwatts of power that Sharps MemoryLCD displays have. They often beat comparable EInk screens in power draw." - dragontamer
  • "The LCD pixel (aka the liquid crystal) is a glorified capacitor, it takes some power to charge but it's exceptionally 'light' compared to eink. That's why LCDs can go faster and faster. It's just physics. A capacitor / twisted crystal uses less power to turn on or off than EInk." - dragontamer
  • "What you can't do is 1) '% of power per frame' figures that LCDs have, with 2) persistence, and 3) long life. (1, 3) is LCD, (2, 3) is E Ink, (1, 2) is LCD abused as if it's E Ink at expense of rapid degradation, and (1, 2, 3) is the holy grail." - numpad0
  • "Mirasol IMOD had 15-60Hz near-zero static power displays. Color was lower contrast of course." - bobmcnamara
  • "Transflective LCD screens ("e-paper") compete with e-ink currently." - dredmorbius
  • "Monochrome e-ink has a better resolution and contrast ratio than old-school LCD devices (I'm comparing my experiences with a Palm Pilot in the 1990s and an Onyx BOOX in the 2020s). LCD can refresh far faster, in the 100+ / 100s Hz range, where typical e-ink refresh rates in my experience have been in the single-digit to low-double-digit Hz range (video is doable but far from ideal)." - dredmorbius
  • "ThrowawayR2: E-Ink's other advantage is being a non-emissive display. Transflective LCD displays have low contrast. I'm literally holding an e-ink tablet over the transflective monitor I'm typing this on and the difference in contrast at the same ambient illumination is considerable. If the price were right, I'd definitely consider a 75 Hz e-ink monitor even if the power draw was more than a normal LCD monitor."

Desired Future E-Ink Applications and Features

Users express aspirations for more advanced e-ink devices, including color displays, larger screen sizes for specific use cases like sheet music, and better performance for tasks like scrolling through notes.

  • "I'd be willing to make the trade for e-ink's contrast." - Wowfunhappy
  • "I want something that's ~16" but doesn't cost an arm and a leg, for displaying sheet music. Still haven't found anything that's suitable. Plenty of people I know use the 13" iPad Pro, but between the glare (stage lights can be intense) and the roughly-letter-paper size, I still prefer sheets of paper." - kayson
  • "I want color e-paper that can show large paintings, like 30” x 40”. When is that coming out finally !!" - EGreg
  • "I play chess on a e-ink smartphone and it is a nice break for my eyes in the evening. I can not wait for the moment when I would be able to code on a nice colored e-ink desktop screen." - dezmou
  • "laserbeam: I love my e-ink tablet. Regardless of manufacturer (remarkable, boox, supernote…), all e-paper tablets have one major performance problem: quickly scrolling through multiple pages of notes. No idea if the display is the limiting factor, or the cpu, but I’ve hit this issue on all tablets I’ve used. If you like riffling through pages in you paper notebook, you will hit the limit too. I know at least 2 people who stopped using their tablets over time because of this issue. If this tech helps solve that problem, it’s more important to me than an eink monitor."
  • "notepad0x90: I'm ok with E-paper's capabilities, the problem is cost. Even though it can't display all the content TFT & LCD can, it costs a LOT more. I'm not a hardware person, I just looked into the cost of working on an E-paper based wall-spanning display and just stacking LCD's and doing something ugly was much cheaper. I suspect it has to do with the wholesale economics and its demand."
  • "BobbyTables2: I wish e-paper would soon reach the realm of my wallet. Sick and tired of seeing really neat announcements with pricing out-of-bounds for hobbyists. (At least those who aren’t prepared to spend thousands just to experiment with a new toy screen)"
  • "h4ch1: What's the best e-paper/e-ink display on the market with a good price-performance ratio that I can use to tinker around with? I basically want to build a custom e-reader with a RasPi Zero for learning/home use, 8-10inches would be great. Don't care much about it being touchscreen."