11 ms·
How does a screen work?
- p44v9n 1y agoSo fascinating!
- qwertox 1y agoNot only was the initial diagram all/explaining, but the "pop"-"pip" on zoom-unzoom of the image was just as nice as playing with a sheet of bubble wrap. Wow, and that ruler on the right side, even with the sound. One of the nicest pages I have been on. And the landing page... https://www.makingsoftware.com/ https://www.makingsoftware.com/ It just keeps on giving.
- consumer451 1y agoThis appears to be a lovely project. I wish the author all possible luck and success. I haven't joined a mailing list in a very long time, but I sure did in this case.
- mrbluecoat 1y agoAdding my congrats as well. The combination of well-written explanations for the semi-technical layperson combined with clear, intuitive graphics is a powerful instruction platform.
- seemaze 1y agoAgreed, very talented communicator. Reminds me of the wonderful work of Bartosz Ciechanowski https://ciechanow.ski/archives/ https://ciechanow.ski/archives/
- the_arun 1y agoSo crisply done. I wish if Dan writes textbooks for all science & math books for High School students. World would be a better place for those who struggle to understand academics.
- kfarber 1y agoAgreed, absolutely stunning diagrams and visual design.
- retrac 1y agoCRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190 https://youtu.be/3BJU2drrtCM?t=190
- snovymgodym 1y ago> It's an illusion. In a sense, all vision is.
- YZF 1y agoThere is some persistence in the pixels/phosphor though so it's not a complete illusion. But yes, your eyes are integrating over the frame. There is also interlacing... I read something interesting recent but I'm not sure if it's true or not. That as you age your integration frame rate decreases.
- jagged-chisel 1y agoWhen I learned how TV worked at the beginning of television history, I found it super cool that the camera and all the TVs across the country had their scanning beams synchronized. That camera was driving your TV, almost literally.
- eastbound 1y agoI only recently found out that the tech to save images wasn’t invented, so they couldn’t display a revolving logo between shows. So… so the BBC had a permanent real-life logo with a permanent camera in front of it. So yes, any image was extremely ephemeral at the time. PS: Apparently it’s called a Noddy, it’s a video camera controlled by a servomotor to pan and tilt (or 'nod', hence the name Noddy): https://en.wikipedia.org/wiki/Noddy_(camera) https://en.wikipedia.org/wiki/Noddy_(camera)
- charcircuit 1y ago>The fact that they ever made it out of the research lab and into our homes is astonishing to me. What is astonishing about LCDs? I don't mean to diminish the difficulty of scaling up the process, but if you think of early LCD displays they don't seem farfetched to be shipped to consumers.
- YZF 1y agoOne random example is that your eyes are extremely sensitive to the tiniest defect or variation. So making a large display that looks good and is uniform is very challenging. Not to mention scaling up all the various processes like the photolithography and working with very large and thin glass panels. It's all engineering but it's surprisingly hard to move things from the lab to manufacturing at scale. Years and years and lots of problem solving. Some efforts/approaches fail and you never hear of them.
- charcircuit 1y agoYou are moving the goal posts from it being a consumer product to requiring it to be large, good, and uniform. Yes, there was engineering work to make such a consumer product, but it is something I would expect there to have been line of sight for.
- YZF 1y agoI was just giving one example. The first LCD products I remember were things like 7 segment digital watches and calculators where the LCD was passive and the "pixels" were large. I am not super familiar with how that went from lab to consumer product but I imagine even there it was non-trivial. It took a long time to progress to modern LCD displays. It took years to get from small black and white displays, to small color, to larger and larger displays. Productizing this stuff includes building machines, factories, ASICs, and figuring out a lot of technology as you go along. Some interesting history here: https://www.varjukass.ee/Kooli_asjad/Ylikool/telekom/displeide%20ehitus,%20stereokujutis.pdf https://www.varjukass.ee/Kooli_asjad/Ylikool/telekom/displei...
- YZF 1y agoPut a magnifying glass on your LCD display and you can see the sub pixel pattern... A few decades ago I worked on a huge machine that made LCD color filters.
- nu11ptr 1y agoAm I the only one who read this as the terminal program "screen" (the terminal multiplexer)?
- nyarlathotep_ 1y agoHa, I did that too.
- vicurve 1y agoIt was 50/50 for me as well but the screen source code is fairly readable and if I remember right eerily over-commented for Unix code! The function names actually make sense.
- ksec 1y agoLCD on paper you see lots of drawbacks, in practice modern state of the art LCD for TV is pretty damn good. We will soon have RGB LED Backlight LCD with WHVA+ Panel that is about as wide angle as IPS, 95%+ REC 2020 colour, and 1-2ms response time. Phosphorescent blue OLEDs should reduce current OLED display energy usage by 20-30%. But it still seems to be way off for phones and mass usage.
- hinterlands 1y agoI think it's fairly common for technologies to get really good just as they're becoming obsolete. Vacuum tubes, CRTs, optical disks, photographic film... in fact, they're often in some respects better than the early generations of the technology that replaces them. But OLEDs just have too many advantages where it actually matters. Much lower power consumption, physically more compact (no need for backlight layers), etc.
- tempestn 1y agoYou might add ICE cars to that list. All kinds of cool stuff being developed around small turbocharged engines and other efficiency gains, excellent transmissions, etc.
- bitwize 1y agoFor me, OLEDs fall into a category exemplified by Anton Gudim's "YES, BUT" comic series. YES, OLEDs consume less power, offer truer color reproduction, and are physically more compact. BUT, they are prone to CRT-like burn-in. SSDs, the same thing. YES, SSDs are much faster and immune to mechanical failure. BUT, they tend not to last as long as HDDs due to limited write cycles, and their price per GiB is still much higher.
- kec 1y agoNone of that really helps LCDs primary downsides of poor contrast ratio and relatively high energy consumption. Backlit displays will always inherently score worse on these metrics vs self emissive displays.
- vicurve 1y agoI can appreciate these articles as they are but I personally don’t like them. They are junk food level of infotainment to me. Something I’d find on a Wikipedia summary section that covers general points. A CRT - to name one - is a device whose actual understanding will challenge people in profound ways. To ask “how does a screen even work?” and to begin to answer this question will require a bit more than a summary form of “thing goes from point A to point B”. The history of this discovery is a stack of books and in and of itself is fascinating - the experiments and expectations and failures and theories as to why and how. I suppose I just expect more of the site. The illustrations are nice. Oh and my moniker is just a coincidence.
- meindnoch 1y agoAgree. It is the equivalent of a coffee table book.
- jorkingit 1y ago[flagged]
- consumer451 1y agoSure, but I sent this to my nerdy early teen nephews and they actually liked it! This is no small feat.
- fabiensanglard 1y agoThe drawings are really good. Any idea what tool is used to make them? I emailed the author but have not heard back.
- cyberlimerence 1y agoFrom the FAQ on the main page: > How do you make the illustrations? > By hand, in Figma. There's no secret - it's as complicated as it look
- benetttttt 1y agowhat a beautiful project. cant wait for this to be completed
- Sharlin 1y agoCRT displays are one of those analog technologies that are arguably much cooler than their digital successors. Think – a literan raygun, a particle accelerator, inside your monitor, creating the image you're looking at.
- pavlov 1y agoActive matrix flat panels felt like incredibly cool technology when they became available in the 1990s. Each individual pixel is driven by a transistor and capacitor that actively maintain the pixel state? Insane manufacturing magic. Dead pixels used to be a big problem with LCD displays. Haven’t thought about that in at least twenty years.
- Sharlin 1y agoTrue – but on the other hand, it was "only" a few million elements, and very large ones, compared to, say, the DRAM chips of the time. Monitors certainly make the engineering feat more tangible, though!
- _kb 1y agoIt’s certainly one the bits of tech that would be an insane pitch if invented today: “Yes, please stick your face in front of this particle accelerator. I assure you, it’s completely safe. You may experience some visual side effects but that’s completely intended.”
- nedt 1y agoIt's much cooler if you haven't used it. That mass of a 19in was crazy. Then you had all of those that had the high pitched noise. And if you were unlucky you had to degauss them. Cool concept, but in practice the digital successors are better.
- timw4mail 1y agoMostly. But multi-scanning to different resolutions is something I'll miss.
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- LocalH 1y agoI have to take issue with the usage of the terms "pixel" and "subpixel" with regards to CRT. CRTs do not display discrete pixels. They display discrete scanlines, each one made up of a smoothly varying voltage across the line (and thus resolution is a function of both the DAC in the display device in the case of systems that generate a digital signal and then convert it to analog for display, and the hardware inside the CRT monitor). Also, there is no mapping between any "pixels" represented within that varying voltage and the separate color phosphor dots. Even "digital RGB" isn't digital in terms of the CRT. It's only "digital" because each color channel has a nominal on and off voltage, with no in-between (outside of the separate intensity pin). However, the electron gun still has a rise and fall time that is not instant. Displays didn't truly become digital for the masses until the LCD era, with DVI and HDMI signals. Even analog HD CRTs could accept these digital signals and display them.
- rahimnathwani 1y agoYears ago I had an LG 32" wide-screen CRT TV. I chose that model because it had a VGA port. It advertised a resolution of 640x480. I was thrilled when my computer let me choose a resolution of 848x480, and it worked perfectly. Back in those days, the web was usable at that resolution.
- mikepurvis 1y agoIt still basically should be, so long as well-designed sites give you the "small screen"/mobile layout. Even apart from that, a lot of laptops still have 1280x800 as the default resolution, and that's only double the width of 640x480. Honestly, I'd actually be more worried about OS and browser chrome eating up the space than websites themselves being unusable.
- rahimnathwani 1y agoThe 480 height is the bigger issue. Try browsing on your phone in landscape mode.
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- killjoywashere 1y agoI happen to have a stereo microscope at my desk, so I put my Pixel 9 under there. At 100x mag (10x ocular x 10x objective) it looks like there are 3 layers: as I move my head around slightly (so the image is moving over my retinas), the blue moves faster and the red almost stays still, with green somewhere in the middle.
- mikecarlton 1y agoSee also the author's page linked from the post. More very well-done content https://typefully.com/DanHollick https://typefully.com/DanHollick
- vojtechrichter 1y agoVery cool looking website. Looking forward to the quality content
- apricot 1y agoThis is a great project. I want to show it to as many teenagers as I can.
- stalco 1y agoThe ticker on the right is quite nice, but I perceive the sound as coming from within my nose (if that makes any sense) to the point that I thought something was going on with my sinuses for a full 3 seconds, and got panicked. Wonderful content and website otherwise!
- ekunazanu 1y agoEverything on the site seems high quality, very much looking forward to the upcoming articles
- perching_aix 1y agoThere are some sentences in this that are technically vague enough to pass, but I don't think are strictly speaking correct, and I believe will likely lead to a mistaken understanding: > modern displays don't paint the image line-by-line (...) They light up each pixel simultaneously, refreshing the entire display at once. The entire screen area is lit all the time now, yes, but refresh still typically happens line by line, top to bottom [0], left to right [0], for both LCDs and OLEDs. It's a scanning refresh, not a global refresh (sadly). You can experimentally confirm this using a typical smartphone. Assuming a 60 Hz screen refresh, recording in slow motion will give you enough extra frames that the smartphone camera also likely operating in a scanning fashion (rolling shutter) won't impact the experiment. On the recording, you should see your screen refreshing in the aforementioned fashion. [0] actual refresh direction depends on the display, this is for a typical desktop monitor
- kurthr 1y agoI was glad they at least mentioned how IPS (PLS) and VA differ from older TN. But you're right both LCD and OLED refresh a stored voltage on the cell (or caps) on a roughly line by line (OLED can easily be 5 clocks on the GIP to cancel internal transistor offset voltages). I was mostly annoyed that they didn't mention the circular polarizer on OLEDs. Although there is discussion of going to color filters with Quantum Dot OLED, the circular polarizer is what makes the blacks so black on mobile OLED devices. Also, didn't really mention pentile RGGB sub-pixel pattern which is dominant in mobile OLED (which is more than 50% of devices). Now they're moving to "tandem" stacked OLED for higher brightness and lower current density, but no latteral sub-pixel pattern.
- perching_aix 1y agoThere were a few things I personally found lacking as well, albeit they're fairly minor. Regarding CRTs, at the vector CRTs section, they mention "they were mostly monochrome and so the phosphor dots could be tightly packed" - this is not true either I believe, monochrome CRTs had a uniform phosphor coat on the inside, no subpixel patches. I'd have also liked if they delved a bit into the decay times of the various phosphor chemistries used for color CRTs, and how they compare to LCDs and OLEDs. It's an entertaining comparison, grounds motion performance related discussions really well. Regarding LCDs, I missed the mention of multi-layer LCDs, especially since they bring up tandem OLEDs. Regarding OLEDs, now that you mention, the subpixel layouts were left unaddressed. Regarding quantum dots, I missed both the mention of QDEL as a somewhat promising future contender, and the mentioning of the drawback of their typical implementation. External light also provides them with energy to activate, which I believe is at least partially the cause behind the relatively poor black levels of QD-OLEDs in environments with significant ambient light (+ something about it not being possible to put a polarizer in front of them?) I was also generally expecting a more in-depth look by the title, would have loved to learn about the driving electronics, maybe learn about why OLEDs aren't ran anywhere near as fast as their full potential (I'd assume throughput limitations), etc. Overall, it basically only covers as much as my own enthusiast but not in-the-area self gathered over the years too.
- massung 1y agoI know this is HN, but I honestly clicked this link initially thinking it was going to be a detailed analysis of how screen plays are constructed and executed in football. It’s late and time for bed! LoL.
- MarcelOlsz 1y agoI was expecting a Ciechanowski link lol.
- rocqua 1y agoI'm much more interested in the hardware driver. This thing gets digital encoded input, has to decode it, and then multiplex it to 8 million pixels. 60 times a second. Being able to hit at least 4 million different levels (talking about 4K 60fps 12 bit color). The input is roughly serial, so it takes a massive serial to parallel conversion.
- Aardwolf 1y agoYeah, with an electron beam it's clear that it's a continuous signal and a single beam is being controlled, but how do you drive millions of individual digital pixels all at once, how does the signal get routed correctly to each one if them?
- p_l 1y agowith older HDMI/DVI displays, AFAIK you sync pixel clock to "address generator" for the matrix, with major issue becoming scaler AFAIK. DVI (and thus older HDMI) being essentially "VGA that skipped Digital to Analog conversion" you're riding the beam, including porches.
- myself248 1y agoBut the output of the scaler chip is still serial, just now it's guaranteed to have the same dimensions as the panel itself, and includes whatever OSD overlay might be active, and any gamma/contrast/whatever adjustments. I believe in some cases, this is also where dithering takes place, to take a 6-bit panel and try to give it 7-bit (or, yikes, 8-bit) color depth by PWMing pixels that have intermediate values. Look at the connector pinout of the panel itself. There's only 50 pins or so, and a lot of them are grounds. Whether the scaler-to-panel format is eDP, or LVDS (FPD-Link), or V-by-One, it's all still differential serial lanes at that point. Around the perimeter of the panel, then, are the actual TCON and row/column driver chips, bonded right to the ITO traces on the glass, flip-chip-on-glass style. These have an outrageous number of pins, and directly connect to the gate (row) and source (column) traces. It's here that the serial becomes parallel, and the next stop is the transistors themselves (hence the MOSFET signal terminology of gate and source) in the individual pixels. Older displays would have basically a bunch of serial-to-parallel register chips with each one's SO connected to the next one's SI. I ran across a fasincating video of replacing a bad chip in such a display, which happens to be gas plasma so the voltages involved are also pretty high too: https://www.youtube.com/watch?v=6W3H5wOy5sY https://www.youtube.com/watch?v=6W3H5wOy5sY
- nedt 1y agoIf the author is here. Would be nice if you could give a hint on all the disabled chapters. Either a tooltip or even just a title attribute. Are they paid? Do I have to login? Not ready yet?
- horizion2025 1y ago[dead]
- frankus 1y agoTeletypes were long gone by the time I started playing with computers, but computing definitely existed before CRTs were the dominant output format.
- cainxinth 1y agoBeautiful diagrams. That one showing how light polarizers work explains it better than any I’ve ever seen before.