[HN Gopher] Don't use 7-segment displays (2011) [pdf]
___________________________________________________________________
Don't use 7-segment displays (2011) [pdf]
Author : fanf2
Score : 110 points
Date : 2024-07-09 17:42 UTC (5 hours ago)
(HTM) web link (harold.thimbleby.net)
(TXT) w3m dump (harold.thimbleby.net)
| anotherhue wrote:
| I 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 wrote:
| Only 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 wrote:
| Ultimately, 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 wrote:
| The 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 wrote:
| > 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 wrote:
| I suspect that simple LCD displays have the lowest power
| consumption (see wristwatches, etc).
| xxs wrote:
| They are not even remotely comparable when it comes to
| readability/contrast.
| hoherd wrote:
| For that we have Memory LCD
| https://www.adafruit.com/product/3502
| jonny_eh wrote:
| How do those compare on price though?
| moffkalast wrote:
| Well that one's from Adafruit, so probably 10x the price
| of what's commonly sold.
| nebula8804 wrote:
| While 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.
| ClassyJacket wrote:
| Apparently Sharp introduced the technology in 2009, so
| perhaps there's a patent expiring soon?
| outworlder wrote:
| > Maybe cheaper, but what about power consumption? I would
| have expected them to need significantly more, which might
| matter for battery-powered devices.
|
| Seven segment displays are quite power hungry relative to
| what information they can display. LCDs sip power, the issue
| is their backlight.
| bobmcnamara wrote:
| Seven segment is a pixel layout.
|
| LCD/LED are pixel types.
|
| Seven segment LCDs are super low power, and can be made to
| reflect through ambient lighting.
| olyjohn wrote:
| Like how my calculator runs off of the the tiny solar
| panel that is built in and is powered by ambient light in
| the room.
| gedy wrote:
| I think some folks might be thinking of the older light-
| emitting 7 segment displays which used more power.
| eschneider wrote:
| Ah, but 7-segment displays are far easier to drive from a
| microcontroller, so even if an LCD is cheaper, it might make
| for a more expensive system.
| numpad0 wrote:
| Depends. I2C only takes two I/O pins.
| samtho wrote:
| That's only part of the equation. Grid displays require a
| lot more memory and often power to drive. By contrast, a
| seven segment display requires 7 (or 8) LEDs and 8 bits per
| digit on the output stage, 4 bit in BCD, which can be fed
| via a shift register.
| dfox wrote:
| Almost any other display that you will reasonably use in
| a application that makes sense for segmented multiplexed
| LEDs will integrate internal controller, so instead of
| having to refresh the thing somehow you have a thing that
| is simply an peripheral hanging of some or other bus that
| just does its thing. And well, such things tend to be
| cheaper than seven segment LEDs (there is a reason why
| random almost disposable crap has graphical monochrome
| OLED panels)
| petsfed wrote:
| Granted, but as a sibling states, the other factor is
| firmware complexity. I can theoretically drive a high-
| resolution display on an 8-bit micro (although it may
| require with some clever bit banging to get I2C to work at
| all) but its trivial with a 7-segment display.
|
| And as a bonus, you don't have to involve anymore UI/UX
| design than to answer the question "what number should go
| here?"
| numpad0 wrote:
| It'll be microcontroller equivalent of running full
| GNU/Linux to control an Internet of e-waste tea kettle,
| but CH32V003 + SSD1306 OLED + passives takes less than 10
| parts total, no crystals needed, has plenty sample codes
| online, and costs ~$2 combined. Depending on the price of
| the final product, it could make financial or product
| design sense.
| petsfed wrote:
| In a medical or aerospace application, that added
| firmware complexity could be a non-starter. Not from a
| price, or even e-waste standpoint. Its that proving the
| thing is safe is a lot harder when its complex. That's
| the real point of keeping it dumb.
| krisoft wrote:
| Also i don't entirely understand the LCD vs 7-segment
| comparision. In my mind many (perhaps most?) 7 segment
| displays use LCD technology.
|
| Are we comparing here pixel-matrix LCD screens with 7-segment
| screens?
| throwway120385 wrote:
| Some 7-segment displays are vacuum-fluorescent rather than
| LCD. These displays are significantly brighter.
| HeyLaughingBoy wrote:
| Legacy 7-segment displays use LEDs. Specifically, one LED
| per segment. The LCD version arose when the power
| consumption of the LED-based ones was an issue.
| ClassyJacket wrote:
| You're correct. 7-segment is a display layout, not
| technology - I think it's implied they mean pixel matrix vs
| 7 segment.
| ChickeNES wrote:
| I'm not convinced that matters much in 2024, especially when
| this article singles out safety critical systems. Such
| systems are likely to be fairly expensive to being with, so
| the marginal cost of adding a display would be minuscule
| compared to testing and regulatory costs (not to mention the
| increase in fault tolerance versus a failed segment causing
| an incorrect reading).
| dylan604 wrote:
| A cracked LCD screen also makes the display unreadable.
| There are all sorts of ways for anything to fail, so
| calling out one failure method of one thing while ignoring
| similar failures for the device being compared comes across
| as very short sighted
| yobert wrote:
| Yes but a cracked LCD is much more obvious than a single
| LED segment burning out. Also usually physical damage is
| required to crack an LCD, where as LEDs can burn out
| (albeit rarely)
| nebula8804 wrote:
| The thing I hate about low cost LCD displays is that
| terrible motion blur when you have changing or scrolling
| text. It just screams cheap in my mind. 7 segment never
| had that problem.
| lelanthran wrote:
| > Ah, but 7-segment displays are far easier to drive from a
| microcontroller, so even if an LCD is cheaper, it might make
| for a more expensive system.
|
| It's not all about economics either; I can read a 7-seg
| display from clear across a factory floor from almost any
| angle _in the dark_.
|
| Try reading those low-cost LCDs in the same conditions (the
| dark is worse, because the LCD doesn't have a true black so
| the contrast is lower).
| jwells89 wrote:
| Which is why standalone digital clocks generally still use
| them instead of LCDs, and why I'd like to build a 7-segment
| clock at some point. That condition-agnostic readability is
| hard to beat.
| dfox wrote:
| The reason why most standalone digital clocks use LED
| seven segment displays is that to this day almost all of
| them are built around the same weird PMOS Sanyo ASIC from
| late 1970's.
| xxs wrote:
| OLED suggestion is even worse due to lack of longevity,
| burn-in.
| ComputerGuru wrote:
| > I can read a 7-seg display from clear across a factory
| floor from almost any angle in the dark.
|
| Ironically, this is true at lower power/brightness than
| higher. A few gas stations near me got newer super-bright
| displays and you can no longer make them out at a distance.
| robocat wrote:
| > I can read a 7-seg display from clear across a factory
| floor from almost any angle in the dark
|
| Is it dark when you are on your factory floor? And what is
| it that you need to read across the factory floor?
| northwest65 wrote:
| I'm not a professional, but I find an LCD or OLED is a lot
| easier to drive from a microcontroller than a 7 segment or 4.
| Like a hell of a lot easier.
| delfinom wrote:
| I can produce 3 inch or smaller segment displays for 30 cents a
| pop with up to 50 segments. At a MOQ of just 10k
|
| You can't touch that with TFT/LCDs. Not to mention the current
| consumption of a segment LCD display is measured in microamps.
|
| And the micros that drive segment LCD displays can easily be
| sub dollar.
| sandworm101 wrote:
| Durability and failure modes are also better with segment
| displays, which is why you still see them in military or
| aviation applications.
| Suppafly wrote:
| >small TFT/LCD and even OLEDs are cheaper.
|
| How can that be true?
| rvbissell wrote:
| My guess is: economies of scale, in 2024 (vs say, 1990)
| Suppafly wrote:
| I had considered that maybe new 7-segment displays aren't
| being made, so maybe they cost more for that reason, but
| even that doesn't seem like it'd be true.
| pclmulqdq wrote:
| If you look at distributor single-unit quantities, they are
| close in cost. If you look at hobbyist stores, they are the
| same price (or more expensive for the seven-segment version).
|
| If you ask a factory in China to make you 1 million displays,
| the seven-segment version will be a lot cheaper. That's why
| new products use them. Even at 1k quantity from distributors,
| seven-segment displays are substantially cheaper.
| numpad0 wrote:
| Some Chinese display manufacturers are dumping lots of small,
| easy to use, postage stamp sized monochrome blue-white OLED
| at ~$1.5 apiece from 1 unit with free shipping, which had
| made it a viable replacement for 7-segments, couple power
| LEDs, even decorative logo displays, for small scale
| productions. It's not the case at all for real mass produced
| products, but not everyone is delivering thousands of units
| per month to Walmart.
|
| I personally don't necessarily support "just go graphical"
| sentiment, but such local minima do exist.
| nebula8804 wrote:
| Seems like many suppliers are coalescing on certain
| sizes/designs of OLEDs at the low end. All I see are these tiny
| blue/white displays or 1 inch full color. They all look the
| same and are boring at this point. I was hoping that we would
| get an explosion of different OLED display sizes and designs.
| xxs wrote:
| LCD is much harder to reader, and a lot more complex to drive.
| Vibration wise I'd take potted 7-segment display as well.
| Single color is a benefit.
|
| OLED would have much shorter life, along with burn in - 7
| segment ones tend to display very static info in many cases.
| Rhapso wrote:
| "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 wrote:
| There is: https://www.sparkfun.com/products/18566
| Kon-Peki wrote:
| That 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.
| crote wrote:
| > That display is really hard to read.
|
| Most of that is just due to a lack of contrast. Add a
| slightly-tinted window in front of it to reduce the
| contrast between unlit segment & background, and it becomes
| a lot easier to read.
| wrs wrote:
| 16-segment displays are another longtime standard
| configuration.
|
| https://en.wikipedia.org/wiki/Sixteen-segment_display
| wongarsu wrote:
| The market is flooded with 128x64 1.3" or 0.96" OLED displays.
| You can pick them up for anywhere from $1-$5, probably less if
| you bulk order.
|
| Sure, they bring some complexity. Instead of just driving some
| pins you now need a display library and at least some bitmap
| font. But they provide a lot more fidelity, are vastly more
| readable, and fail in more obvious ways without needing
| periodic test patterns (the flashing 8's or snakes mentioned in
| the paper so you can detect failed segments)
|
| For larger displays the choice becomes more interesting between
| OLED, LED matrices or 16 segment displays, but for small
| devices like those shown in the paper cheap OLEDs make the
| choice easy
| andylynch wrote:
| They are cheap enough now, that they are appearing on
| disposable vapes (?!)
| s800 wrote:
| They also wear out quite quickly.
| Rhapso wrote:
| "display library"
|
| bold of you to assume i have enough memory to drive the
| thing.
| duskwuff wrote:
| The most common models of small OLED displays (SSD1306,
| etc) have a (write-only) framebuffer in the display
| controller, and can be written to incrementally. If you
| structure your visual interface with certain simple
| constraints in mind, you can update it without using any
| additional dynamic memory.
| Rhapso wrote:
| That would probably be 100x more complicated than the
| actual business logic on a small microcontroller and
| there are limits to program memory for the "streaming
| this string to the screen by constantly computing if a
| given pixel is on one at a time" algorithm.
|
| edit addendum; If it was using a 7-segment display, it is
| either really cheap or really simple "a graphical GUI on
| a screen" IS NOT A REASONABLE NEXT STEP.
|
| I think we have radically different expectations of a
| simple embedded system.
| jenadine wrote:
| You can get something like a rp2040 for a couple of $.
| And let a graphic library do the hard work. Eg
| https://slint.dev/blog/porting-slint-to-microcontrollers
| nick238 wrote:
| RP2040 should cost $0.70 in some quantity
| (https://www.digikey.com/en/products/detail/raspberry-
| pi/SC09...) and in low-quantity it's $1 from places like
| CanaKit. That's actually shockingly cheap for an ARM
| Cortex M0; I was assuming your ATmegas and PIC18s with a
| similar pin count (40, 48, 64) would be a bit cheaper,
| but they seem to be around $2-4 in similar low-production
| quantity. Power efficiency won't be anywhere near as good
| with the ARM part, but if you're making a battery-powered
| device, you might be able to use the extra dollar or so
| to make it rechargable, then people care a bit less if it
| eats batteries.
| duskwuff wrote:
| > That would probably be 100x more complicated than the
| actual business logic on a small microcontroller
|
| It really isn't. I've implemented simple UIs on SSD1306
| displays, and it's very easy to work with. The hardware
| is specifically set up to optimize for rows of 8px tall
| text (or multiples of that with a bit more effort). Once
| you have row/column addresses set up, each byte you write
| to the display writes one 8px column of pixels to a row
| and moves the column pointer over by a pixel. Printing
| text is a matter of streaming a sequence of bytes to the
| display.
| smaudet wrote:
| > The market is flooded
|
| Yes, I'd also like to note, the market is flooded with crap.
| Multiple devices I've owned with these "cheap" displays have
| been on crappy, battery-intensive devices. The devices with
| simpler segment (or dot matrix) displays last longer and work
| better.
|
| I get some of the points where extreme legibility trumps
| (nearly) all other concerns, however I'd propose the issue
| could have been solved more simply with more specialized
| segment displays.
| jeffbee wrote:
| Dot-matrix LED display panels seem bulletproof, but I just
| checked the catalog for the 5x7 display driver I know and
| use and it costs $30 per. I guess the people who have
| reliability and legibility concerns like those expressed in
| the article aren't worried about spending $15 per digit.
| Rhapso wrote:
| I think the point would be, you don't need a driver, you
| need a decoder. Those are very cheap.
| bityard wrote:
| Agreed. "Just use a pixel matrix display" sounds an awful lot
| like, "Just use an Arduino."
|
| There are plenty of places where a simple and small
| microcontroller paired with a 4-digit segment display is the
| cheapest, simplest, and most defensible design decision.
| Rhapso wrote:
| It appears we live in a universe where embedded systems
| aren't assumed to be a mission critical device by default.
|
| I'm not going to bother using a microcontroller to solve a
| problem if isn't a use case where the solution needs to be as
| simple and robust as possible.
| TN1ck wrote:
| Some subways have 111 segmented displays, I really like them,
| the refresh rate is stunning. Here is a page selling them [0]
| and here is how they look [1], [2].
|
| [0]
| http://www.reitberger.de/English/Large%20displays/Alphanumer...
|
| [1]
| https://www.reddit.com/r/whatisthisthing/comments/6zsezx/thi...
|
| [2]
| https://www.reddit.com/r/whatisthisthing/comments/e19uaz/wha...
| fitsumbelay wrote:
| I spent entirely two much time battling the two column layout and
| the page-splits. It felt like irony but it probably wasn't.
| rwmj wrote:
| That'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 wrote:
| Isn'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 wrote:
| Not really? If anything, widescreen is better for working
| since it's nicer when you put two windows side-by-side
| bityard wrote:
| "... 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 wrote:
| I 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 wrote:
| In the event that you need to test the display, you should
| just periodically light up all the segments briefly.
| pclmulqdq wrote:
| This happens on startup for many critical systems. They
| turn every segment on and they turn every segment off.
| 1-more wrote:
| Cars, famously.
| pclmulqdq wrote:
| Yeah, almost everyone has seen this self-test happen
| before, but most people don't realize that is what's
| happening.
| jtriangle wrote:
| Usually when these displays initialize they turn on every
| segment before displaying data for that reason.
|
| Also, fairly trivial to detect if a display has a segment
| out and throw a fault if needed. It's also not likely you
| burn out a whole segment at once if you have it wired up
| with that in mind.
| crote wrote:
| If anything, 7-segment displays are _better_ when it comes to
| partial failure, as it 's reasonably easy to add self-test
| functionality which measures the current passing through a
| supposed-to-be-lit / supposed-to-be-off segment.
|
| This would allow for failure detection without the user
| having to explicitly press a test button and look for any
| misbehaving segments. You can't do this as easily (if at all)
| with LCD or OLED.
| neuralRiot wrote:
| > , obviously examination of cost and design trade-offs may
| lead to other decisions, and such decisions should be backed by
| competent empirical evaluation.
|
| It's almost like that is what electronic design means, creating
| a curcuit that works is perhaps the easiest part. Choosing all
| the parameters for the parts to be used and keeping it under
| the target cost is the hardest!
| proee wrote:
| I 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 wrote:
| I also like VFD displays. There is something magical in all
| that green glow.
| keyringlight wrote:
| There'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 wrote:
| The 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 wrote:
| One 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 wrote:
| This 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-seve...
| whartung wrote:
| Just 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 wrote:
| How 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 wrote:
| As a 1970s kid, a tiny brilliant red LED 7-segment digit is the
| most nostalgic display possible!
| whartung wrote:
| Let me introduce you to the Nixie Tube[0]!
|
| 0 - https://en.wikipedia.org/wiki/Nixie_tube
| winrid wrote:
| I 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 wrote:
| Users 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.
| theandrewbailey wrote:
| Over 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 wrote:
| Is 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 wrote:
| > 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 wrote:
| Could also be a design decision. No reason to let the
| engineers make all the choices.
| atoav wrote:
| Huh?
|
| 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.
| doe_eyes wrote:
| Most other display technologies have their downsides too. For
| example, fot-matrix LCDs are far more fragile and more easily
| damaged by sunlight or heat than 7-segment LEDs. If you don't
| discuss that, but dwell on the downsides of 7-segment
| displays, it does feel a bit like a hit piece.
|
| In fact, 7-segment displays aren't even a monolithic
| technology, and not all of the gripes in the article apply to
| every implementation. You have traditional LED models, LCD
| 7-segment displays, and then some OLED flavors, VFDs, and
| even electromechanical designs in niche applications.
| bowsamic wrote:
| Considering the paper does not specify that it has no conflicts
| of interest in the usual place where it would, we should assume
| the author is involved with such manufacturers
| carlosjobim wrote:
| Almost any 7 segmented display could be replaced by an analogue
| gauge. For time, for temperature, for selecting options. When a
| device has a segmented display, I assume it is to cut costs.
| janaagaard wrote:
| Upside down 7-segment display in Futurama:
| https://youtu.be/1Q8E4hls_Zg?si=q5nMASH4PGgvEkHN
| vladde wrote:
| Posy made a wonderful video about different numbered segment
| designs https://youtu.be/RTB5XhjbgZA
| thesnide wrote:
| Well, a TTL clock cannot be made otherwise...
|
| https://leap.tardate.com/electronics101/digitallogic/digital...
| dang wrote:
| Related:
|
| _Don't use 7-segment displays (2011) [pdf]_ -
| https://news.ycombinator.com/item?id=26373405 - March 2021 (78
| comments)
| gweinberg wrote:
| The digits on my watch face look like 7 segments. Works great!
| magicalhippo wrote:
| One 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 wrote:
| so funny that this shows up today. I have been looking into
| connecting seven segment displays to a raspberry pi
| thrwwy6967362 wrote:
| I 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.
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