6 ms·
Don't use 7-segment displays (2011) [pdf]
- anotherhue 2y agoI suppose, but an analogue clock can be misread if held upside-down also, so what's the permitted degree of operator error? Depends on the consequence & domain I suppose.
- kennywinker 2y agoOnly if it doesn't have the indicator numbers. I think most people would notice if the 6 was at the top and the 12 was at the bottom.
- jtriangle 2y agoUltimately, this is trying to solve a human problem with tech, which is rarely a solution. If a display has garbage data on it because it's broken, the untrained person trying to read it is going to misread it regardless of the failure mode. That and you can make 7-segment displays fault tolerant, ie, detecting when segments are out/partially out, because you can measure current draw. Not exactly difficult, also not exactly common because they don't really fail that often.
- a2800276 2y agoThe publication date is unclear, but the latest citation is 2011. It doesn't make economic sense anymore to use seven segment displays in new products, small TFT/LCD and even OLEDs are cheaper. It probably does make sense to use them with legacy equipment that require a large certification effort (most of the examples are medical). The advice the author gives for situations where seven segment displays are used is good, though. What really doesn't make sense is using a seven segment font on a high resolution device to make the product seem more technological, I guess, but I don't think that was mentioned.
- gray_-_wolf 2y ago> It doesn't make economic sense anymore to use seven segment displays in new products, small TFT/LCD and even OLEDs are cheaper. Maybe cheaper, but what about power consumption? I would have expected them to need significantly more, which might matter for battery-powered devices.
- mytailorisrich 2y agoI suspect that simple LCD displays have the lowest power consumption (see wristwatches, etc).
- xxs 2y agoThey are not even remotely comparable when it comes to readability/contrast.
- hoherd 2y agoFor that we have Memory LCD https://www.adafruit.com/product/3502 https://www.adafruit.com/product/3502
- jonny_eh 2y agoHow do those compare on price though?
- moffkalast 2y agoWell that one's from Adafruit, so probably 10x the price of what's commonly sold.
- nebula8804 2y agoWhile this display is really slick, it seems like it is still not available under multiple suppliers? If thats the case. that means its going to be more pricey than other options. I cant seem to find many cheap options on alibaba/aliexpress.
- Rhapso 2y ago"Just use a high resolution display" doesn't seem like the corect remedy. Next cheapest would be a low resolution LCD display, (30x80) that has its own set of issues. 7 segments at minimum provide for high visibility even if they fail at high readability. note: price doesn't have to be money, complexity is expensive Why isn't there a market for 14-segment displays or other simple alphanumeric displays? edit: Childen comments use the phrase "for a few more $" a lot and i think they miss the point that if that was acceptable and easy we wouldn't be talking about it.
- maxwell 2y agoThere is: https://www.sparkfun.com/products/18566 https://www.sparkfun.com/products/18566
- Kon-Peki 2y agoThat display is really hard to read. I would say that if you're going to use a 7-segment display, it would be helpful to add a "test/diagnostic" button that does a pattern in which all segments are lit up in a predictable order, does a TOP pattern in which only the top segments are lit (to allow for device orientation), and then goes back to displaying exactly what was on the display prior to pressing the button.
- wrs 2y ago16-segment displays are another longtime standard configuration. https://en.wikipedia.org/wiki/Sixteen-segment_display https://en.wikipedia.org/wiki/Sixteen-segment_display
- fitsumbelay 2y agoI spent entirely two much time battling the two column layout and the page-splits. It felt like irony but it probably wasn't.
- rwmj 2y agoThat's sadly all scientific papers. It makes a lot of sense on a printed page, and possibly on a vertical (portrait) monitor, but rarely on a 16:9 laptop screen or phone.
- _Microft 2y agoIsn‘t it rather sad that all screens seem to be purely optimized for video consumption today? Even on devices that are meant for work?
- ChickeNES 2y agoNot really? If anything, widescreen is better for working since it's nicer when you put two windows side-by-side
- deleted 2y ago[deleted]
- bityard 2y ago"... For Critical Applications" is the missing second part of the headline. Where critical applications are basically anything involving healthcare, piloting, or safety. I don't fully agree with all of the arguments presented in the article, but I feel like a lot of commentors here are going to miss that.
- zzo38computer 2y agoI don't fully agree either, but some of them make sense. But, some of them do make enough sense for some kind of critical applications, that it is worth to consider the alternatives (although power usage should also be considered). As items (iii) (although it incorrectly says "(ii)") and (iv) of the caption of figure 1, are reasonable considerations. There is also the consideration of faulty displays, in case a segment stops working (although you can mitigate this problem somewhat, by adding a test switch to light up all of the segments). About decimals, one possibility (depending on the application) is to require a fixed position for the decimal point and add a wider gap between the digits at that position, which improves the clarity. They also mention, "the user cannot see the difference between entering zero, or entering zero then decimal point". This is a problem on many hand-held calculators but it is easy to avoid, by not displaying the decimal point unless it has been entered explicitly (or if the result is being displayed). Upsidedown (also mentioned in the article) is also a reasonable consideration, although there are ways to mitigate that too.
- throwway120385 2y agoIn the event that you need to test the display, you should just periodically light up all the segments briefly.
- pclmulqdq 2y agoThis happens on startup for many critical systems. They turn every segment on and they turn every segment off.
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- proee 2y agoI have a love of electro-mechanical seven-segment displays. For scoreboards and timers, I feel like these are less intrusive than modern electronic display scoreboards. There is something magical about seeing the score "flip" when a point is scored.
- lstodd 2y agoI also like VFD displays. There is something magical in all that green glow.
- keyringlight 2y agoThere's definitely a certain style with VFDs that I'm a little surprised hasn't been adopted by people looking for a retro/cyberpunk aesthetic. I was looking into them when it seemed my decades old alarm clock might need a replacement, and they seem quite rare which I assume the economies aren't there in making something more complex and delicate. Interestingly there's a few clocks repurposing cooker displays, I'd guess a manufacturer had a large stockpile of displays for models they discontinued early and liquidated them.
- elijahbenizzy 2y agoThe title display is very clever but I really wonder if it would have as much of a punch if they displayed that one extra line on the "m"
- 486sx33 2y agoOne very nice thing, dependent on use case of course, is that 7 segment displays are very simple to wire up and use. They can be easily used for analog circuits, without any digital micros at all if needed. You can just grab all the pins to say 8 and wire them to vcc and it works. They are just led lights, arranged a particular way You can even drive them with something like a 555 timer or other 74 series ICs if needed to make basic and very robust monitoring systems. They are very tough, can’t easily break or be destroyed by heat or cold They have a place.
- 486sx33 2y agoThis is an example with a 555 and a cmos IC, but 74 series TTL IC could be used too. Personally more comfortable breadboarding TTL circuits myself but that’s just because I’m old https://circuitdigest.com/electronic-circuits/555-timer-seven-segment-counter-circuit https://circuitdigest.com/electronic-circuits/555-timer-seve...
- whartung 2y agoJust reminds me of stumbling across a Hex -> Segment LED decoder chip. The chip was $17. A RPi 0 is (was) $5. Just one of those "Not in Kansas anymore" moments.
- Rinzler89 2y agoHow much do the software development, and sw bugs in production of doing it on the RPi cost you vs the battle tested hardware hex decoder? Just because you can do something on a RPi doesn't always mean you should.
- mikeInAlaska 2y agoAs a 1970s kid, a tiny brilliant red LED 7-segment digit is the most nostalgic display possible!
- whartung 2y agoLet me introduce you to the Nixie Tube[0]! 0 - https://en.wikipedia.org/wiki/Nixie_tube https://en.wikipedia.org/wiki/Nixie_tube
- winrid 2y agoI repair old timing equipment (think Race America, JACircuits, etc) as a side hobby, and a lot of it is large 7 segment displays with individual LEDs in series for each segment. I am so glad people didn't try using an LCD display or similar, I'd never be able to fix them when the pixels/display panels go bad and the original manufacturer is long out of business. LEDs, shift registers, mosfets... all serviceable.
- ToucanLoucan 2y agoUsers fixing things make the stock market sad. Better to force them to spend hundreds on a new thing then chuck the old one in the garbage even though it's 99% functioning.
- winrid 2y agoUnfortunately some motorsport event organizers barely break even, especially post-covid in CA, although it is picking up slightly this year. It is hard for them to justify $2-4k for a new display or timing system, whereas it's a few hours of work for me to do most repairs.
- rasz 2y agoLCD is doable, it would just take you more time and research to come up with stable cheap solution. LCD are driven by AC at rather pedestrian frequencies, nothing an RP2040 (rp pico) couldnt handle. https://www.eevblog.com/forum/blog/eevblog-1044-lcd-technology-tutorial/ https://www.eevblog.com/forum/blog/eevblog-1044-lcd-technolo...
- theandrewbailey 2y agoOver the past 10 years, I've noticed that most gas stations near me have replaced their pumps. They look like they have 7 segment displays, but if you look close (as you do when you're standing next to it pumping gas), they are actually high resolution LCDs showing numbers in a 7 segment font. I'm sad for what improvements could be had, but aren't.
- deweywsu 2y agoIs this a hit piece by a high-definition display manufacturer? It seems like an unnecessary litany of detractors against one technology without a lot of alternative solutions or trade-offs with others. At the end, there are only 3 sentences that could be called alternatives with the heading "use high resolution displays". Making a "helpful" paper that only lists problems without comparisons or solutions misses all the reasons one would use a 7-segment display (mentioned in the comments here so I won't repeat). There's nothing wrong with this technology. The title "don't use" is too inclusive and is not supported by the paper. I think "Consider not using in certain applications" would have been more appropriate based on the paper's body.
- JohnFen 2y ago> Is this a hit piece by a high-definition display manufacturer? This was the exact thought I had. The paper strikes me as being very odd, and the arguments against using 7-segment LEDs are very thin. I will agree with one thing, though: the right components to use are an engineering decision and as with all engineering decisions, the right choice (i.e., the right set of tradeoffs) needs to be determined on a project-by-project basis. For a given project, that may mean not using a 7-segment LED. Or it might mean that's exactly the right choice.
- detourdog 2y agoCould also be a design decision. No reason to let the engineers make all the choices.
- atoav 2y agoHuh? As someone designing electrical circuits that might or might not use a 7-digit display this seems rather to be a guide for which use cases to avoid them. Electrical engineers sadly sometimes don't think about that at all and slap what they know onto everything. When you have a medical device where a reading error or ambiguity can have serious consequences you might want to be aware of that. There are 7-segment-display usecases where that is not an issue irrelevant, e.g. because you have enough contextual clues to not hold the device wrong and read it upside down or because the potential damage from a reading error is irrelevant. But this is still a design consideration one should be aware of. Especially in times where 7-segment displays aren't necessarily the cheapest option.
- janaagaard 2y agoUpside down 7-segment display in Futurama: https://youtu.be/1Q8E4hls_Zg?si=q5nMASH4PGgvEkHN https://youtu.be/1Q8E4hls_Zg?si=q5nMASH4PGgvEkHN
- vladde 2y agoPosy made a wonderful video about different numbered segment designs https://youtu.be/RTB5XhjbgZA https://youtu.be/RTB5XhjbgZA
- thesnide 2y agoWell, a TTL clock cannot be made otherwise... https://leap.tardate.com/electronics101/digitallogic/digitalclockkit/ https://leap.tardate.com/electronics101/digitallogic/digital...
- dang 2y agoRelated: Don’t use 7-segment displays (2011) [pdf] - https://news.ycombinator.com/item?id=26373405 https://news.ycombinator.com/item?id=26373405 - March 2021 (78 comments)
- gweinberg 2y agoThe digits on my watch face look like 7 segments. Works great!
- magicalhippo 2y agoOne thing 7-segment displays does better than LCDs and OLEDs is refresh rate. They can have a very high refresh rate, and this can help detect noise or variation in the signal. I have two lab power supplies, one with a 7-segment display and one with an OLED. The 7-segment one allows me to easily see issues with the circuit due to the refresh rate, such as unwanted oscillations, which can be completely masked by the comparatively slow refresh rate of the OLED. I won't necessarily see each value, but I'll notice a slight blurring of the least significant digit for example.
- jccalhoun 2y agoso funny that this shows up today. I have been looking into connecting seven segment displays to a raspberry pi
- thrwwy6967362 2y agoI actually prefer 7-segment displays as a user over high-resolution alternatives. I love the 7-segment displays in my Casio watch, calculator, multimeter, lab PSU and until recently Canon 5D Mark IV (which had a 7-segment-ish display on the top). I switched to Nikon Z8, which unfortunately has a higher-resolution display, which I dislike the look of. It’s all overly smooth sans-serif[1]. I like the jaggedness of 7-segment displays. I’ve also never experienced any of the listed issues with them. Unfortunately, all mirrorless cameras have those high-resolution smooth ones now (if they have the top display at all). The one in Z8 is actually the least bad one I’ve seen. [1]: On higher resolution I generally prefer serif fonts. In particular, for coding I use Go Mono, which is one of very few serif monospace fonts.
- jpl56 2y agothe left-aligned 1 is just impossible. Hurts my eyes.