WEBVTT 00:00.000 --> 00:06.000 Sheldon Destruction? 00:06.000 --> 00:07.000 Yes. 00:07.000 --> 00:09.000 For those on the room. 00:09.000 --> 00:12.000 So Alex, thank you for the last talk today. 00:12.000 --> 00:14.000 Long day already. 00:14.000 --> 00:20.000 Alex is going to talk about e-papers and a shit lot of stuff that I have no fucking clue about. 00:20.000 --> 00:22.000 What it actually means. 00:22.000 --> 00:26.000 But we all thought that it's really amazing, really interesting talk. 00:26.000 --> 00:30.000 And we were all amazed to have that in the energy track. 00:30.000 --> 00:31.000 Thank you. 00:31.000 --> 00:33.000 Go ahead. 00:37.000 --> 00:39.000 Yeah, I'm talking about e-papers. 00:39.000 --> 00:43.000 Maybe you know e-papers like designs on the supermarket. 00:43.000 --> 00:46.000 Like e-book readers. 00:46.000 --> 00:53.000 And my talk is mainly about the type of e-papers you see on the supermarket. 00:53.000 --> 00:58.000 So there's not so much electronics inside. 00:58.000 --> 01:03.000 And normally they cannot display e-gay scales or just limited amount of gays scales. 01:03.000 --> 01:07.000 And yeah. 01:07.000 --> 01:09.000 So why this place matters for energy? 01:09.000 --> 01:12.000 Because we have more more displays. 01:12.000 --> 01:15.000 So that's similar like the last talk. 01:15.000 --> 01:20.000 The devices become cheaper and we are use more more displays. 01:20.000 --> 01:26.000 So we also should think about the power consumption of all this displays. 01:26.000 --> 01:33.000 And we have signature smart meters industrial IoT all this kind of stuff. 01:33.000 --> 01:40.000 And we could use the displays, but there should be a better way. 01:40.000 --> 01:45.000 We could use displays that consume less energy. 01:46.000 --> 01:53.000 But e-papers have some constraints. 01:53.000 --> 01:57.000 Yes, e-papers are also not energy free by default. 01:57.000 --> 01:59.000 They use energy to update. 01:59.000 --> 02:05.000 So it's always thinking about if you have a IoT signage somewhere in your house. 02:05.000 --> 02:10.000 And it's updating a tiny clock in the edge every second. 02:10.000 --> 02:13.000 Then it will wake up every second and use energy. 02:13.000 --> 02:16.000 So it's also thinking about the UI. 02:16.000 --> 02:19.000 How can I use less updates? 02:19.000 --> 02:22.000 Go to sleep faster. 02:22.000 --> 02:23.000 Yes. 02:23.000 --> 02:28.000 But one thing of e-papers is most of them have limited colour and no gays scales. 02:28.000 --> 02:33.000 Or sometimes two gays scales and black and white. 02:33.000 --> 02:38.000 And if you have more colours, then usually they have a much longer update time. 02:38.000 --> 02:46.000 So the update time for a black and white display is in the range of less than a second. 02:46.000 --> 02:51.000 And if you add gays scales, then you come to 10 seconds, 20 seconds. 02:51.000 --> 02:56.000 And then colour displays, you even come to like one minute for an update. 02:56.000 --> 03:02.000 So it's more for only updating the night for a new sign. 03:02.000 --> 03:03.000 Yes. 03:03.000 --> 03:05.000 So how does e-papers work? 03:05.000 --> 03:09.000 The e-papers is built out of small bubbles. 03:09.000 --> 03:15.000 And inside the bubbles are colour particles that are swimming in the liquid. 03:15.000 --> 03:21.000 And usually in the simple ones you have black and white particles. 03:21.000 --> 03:23.000 And their particles are electrically loaded. 03:23.000 --> 03:28.000 So you can move the particles with if you put a voltage on it. 03:28.000 --> 03:34.000 And then you can bring the white particles on the front or the black particles on the front. 03:34.000 --> 03:40.000 You see on this picture microscopic photograph from a e-paper. 03:40.000 --> 03:43.000 The squares are the pixels. 03:43.000 --> 03:45.000 And you see the small bubbles. 03:45.000 --> 03:50.000 And inside of each of these bubbles are hundreds of black and white small particles. 03:50.000 --> 03:52.000 You don't see them on this photo. 03:52.000 --> 03:59.000 And if you go far away, then you only see the rectangle pixels. 03:59.000 --> 04:03.000 And yes, the state of these particles is by stable. 04:03.000 --> 04:07.000 You can let display without power sitting for years. 04:07.000 --> 04:12.000 And it doesn't change. 04:12.000 --> 04:13.000 Yeah. 04:13.000 --> 04:16.000 So how this particles move. 04:16.000 --> 04:22.000 So you bring a voltage field on the pixel. 04:22.000 --> 04:27.000 And then you can move the white and the black pixels. 04:27.000 --> 04:33.000 It depends on the voltage you how fast they move. 04:33.000 --> 04:34.000 Yeah. 04:34.000 --> 04:38.000 And if you reverse the voltage, you come from white to black. 04:38.000 --> 04:40.000 And the other way. 04:40.000 --> 04:45.000 One thing is it's a pure analogue thing. 04:45.000 --> 04:50.000 So if you put voltage on for a longer time, then you will destroy it. 04:50.000 --> 04:53.000 Because the pixel lose their polarity. 04:53.000 --> 05:00.000 And also you have electrosmosis inside the display. 05:00.000 --> 05:08.000 And also the other thing is that viscosity of the fluid changing with the temperature. 05:08.000 --> 05:13.000 So you need to adjust the voltages and the driving times depending on the temperature. 05:13.000 --> 05:16.000 So every display has a temperature sensor inside. 05:16.000 --> 05:27.000 And it adjust the voltages and timings depending on the temperature of the display. 05:27.000 --> 05:28.000 Yeah. 05:28.000 --> 05:31.000 What can we do if you want to have more than black and white? 05:31.000 --> 05:36.000 The first thing you can add RGB color filters on top of it. 05:36.000 --> 05:40.000 So you put like an TFT screen. 05:40.000 --> 05:43.000 You put the color filter over the e-paper. 05:43.000 --> 05:49.000 But the problem is you lose resolution and also you lose contrast. 05:49.000 --> 05:58.000 Because if you have a color filter on it, then on every pixel you only get a small amount of light fluid. 05:58.000 --> 06:05.000 And normally you want to use e-paper displays without the font light. 06:05.000 --> 06:11.000 Otherwise the energy consumption goes up. 06:11.000 --> 06:17.000 The other approach is you can use different colored particles inside the bubbles. 06:17.000 --> 06:26.000 Because the displays are built from a roll that means the small bubbles are produced on a roll of plastic. 06:26.000 --> 06:30.000 And then in a later step put on a display. 06:30.000 --> 06:36.000 You cannot make one small bubbles with red particles and one bubble with green particles. 06:36.000 --> 06:40.000 You have to mix all these particles inside the bubbles. 06:40.000 --> 06:43.000 And then you see the next problem. 06:43.000 --> 06:45.000 We only have two polarities. 06:45.000 --> 06:51.000 So how can we drive more than two kinds of particles? 06:51.000 --> 06:57.000 And the trick is that you make bigger and smaller particles. 06:57.000 --> 06:59.000 So they move faster and slower. 06:59.000 --> 07:06.000 And then if you put the right sequence of voltages on it, 07:06.000 --> 07:11.000 you can move them more or less individually. 07:11.000 --> 07:14.000 But that brings through slow updates. 07:14.000 --> 07:21.000 So that's the cause that you have updates like one minute full color. 07:21.000 --> 07:29.000 So the next thing is now we have this kind of e-paper foil with the colors inside. 07:29.000 --> 07:31.000 How can we make a display on it? 07:31.000 --> 07:36.000 Unlike LCDs or TFTs, we cannot easy multiplex them. 07:36.000 --> 07:40.000 That means you cannot have like lines and columns. 07:40.000 --> 07:43.000 And just drive some line and then move them. 07:43.000 --> 07:48.000 Because our other pixels are affected by the same voltage. 07:48.000 --> 07:53.000 So we need like a back plane for it, 07:53.000 --> 07:56.000 where we are doing the switching. 07:56.000 --> 07:59.000 And usually there is a TFT back plane. 07:59.000 --> 08:04.000 So it's the same TFT back plane as in a TFT. 08:04.000 --> 08:06.000 So it's an area of transistors. 08:06.000 --> 08:09.000 Behind each pixel you have a transistor. 08:09.000 --> 08:11.000 That holds the voltage. 08:11.000 --> 08:16.000 So you can drive millions of pixels. 08:16.000 --> 08:17.000 Yes. 08:17.000 --> 08:19.000 So how does it look like? 08:19.000 --> 08:21.000 It looks similar like this. 08:21.000 --> 08:22.000 You have the driver. 08:22.000 --> 08:25.000 The small bar is the driver. 08:25.000 --> 08:32.000 The small IC that has several thousand of output pins that go into the glass. 08:32.000 --> 08:35.000 And on the other side you have the connector. 08:35.000 --> 08:39.000 And usually you have IC or C or SPI interface, 08:39.000 --> 08:43.000 where you send your pixel data to the display. 08:43.000 --> 08:45.000 Also you see the small bubble there. 08:45.000 --> 08:50.000 That's the connection for the front side of the display. 08:50.000 --> 08:54.000 Because you need you have the TFT back plane on the back side. 08:54.000 --> 09:05.000 You have one single plate of with one voltage against data voltage. 09:05.000 --> 09:08.000 So if you turn it around you see it a bit there. 09:08.000 --> 09:17.000 There is a chip and from here you have all the lines and columns of the display. 09:17.000 --> 09:22.000 And now you have two kind of e-paper displays. 09:22.000 --> 09:26.000 You have e-paper displays with dump driver. 09:26.000 --> 09:27.000 IC is on it. 09:27.000 --> 09:31.000 So you need to supply going to the next line, 09:31.000 --> 09:34.000 sending this voltage on the display, 09:34.000 --> 09:36.000 going to the next line or this kind of stuff. 09:36.000 --> 09:38.000 So you need an external controller. 09:38.000 --> 09:42.000 These kind of displays are usually used in e-book readers. 09:42.000 --> 09:52.000 Because you are much more flexible to and also much faster screen updates with this. 09:52.000 --> 09:57.000 But you need a complicated external IC to do it. 09:57.000 --> 10:05.000 And on all these supermarkets displays you have everything integrated in this IC. 10:05.000 --> 10:09.000 So the whole timing is controlled inside IC. 10:09.000 --> 10:11.000 You have nothing to do with it. 10:11.000 --> 10:14.000 In generates all the voltages you need. 10:14.000 --> 10:17.000 You only have to feed it with 3.3 volt. 10:17.000 --> 10:20.000 And it has a small step up converter inside. 10:20.000 --> 10:23.000 And that's everything for you. 10:23.000 --> 10:26.000 But it's quite limited on the software side. 10:26.000 --> 10:28.000 So you send the image there. 10:28.000 --> 10:30.000 You send the refresh command. 10:30.000 --> 10:35.000 And it even measures the temperature and then doing the magic. 10:35.000 --> 10:39.000 And the interesting thing is, can you hack it? 10:39.000 --> 10:43.000 Can you change the way it does things? 10:43.000 --> 10:47.000 So in the IC there is a waveform that... 10:47.000 --> 10:52.000 Or there are several waveforms depending on the temperature, depending on the color you want. 10:52.000 --> 10:56.000 And usually there are factory programmed inside. 10:56.000 --> 11:02.000 And also usually the manufacturers of the displays they don't want to get you them. 11:02.000 --> 11:07.000 Because yeah, it's not open knowledge. 11:10.000 --> 11:13.000 Yeah, that's a picture of the TFT backplane. 11:13.000 --> 11:21.000 So if you put the e-paper on a microscope, you see the lines and the small bubbles here is the transistor. 11:21.000 --> 11:24.000 And that's the pixel. 11:28.000 --> 11:34.000 So to switch to the display, you need a waveform, 11:34.000 --> 11:42.000 so kind of description, put 70 voltage on the cell for 10 microseconds, 11:42.000 --> 11:45.000 then switch to minus 70 volt. 11:45.000 --> 11:50.000 And then repeat this sometime and then do other magic. 11:50.000 --> 11:57.000 And the idea is, how can we store this with some simple bytes? 11:57.000 --> 12:01.000 So you have one global layer for the backplane. 12:01.000 --> 12:06.000 So you can put only ground on the backplane and switching data. 12:06.000 --> 12:11.000 Trust the pixels, but you can also switch the backplane to get double the voltage. 12:11.000 --> 12:16.000 And then you have waveforms for like black white for grace, 12:16.000 --> 12:18.000 or if it has color for different colors. 12:18.000 --> 12:26.000 So they're the waveform describes how you switch the color. 12:26.000 --> 12:32.000 And inside the normal display, you have like four waveforms, 12:32.000 --> 12:39.000 and then you have 10 sets of these waveforms for 10 different temperature ranges. 12:39.000 --> 12:48.000 And that's stored inside and it looks up the right waveform if you switch to display and then it does the magic. 12:48.000 --> 12:55.000 So how this kind of waveform looks, it looks similar like this. 12:55.000 --> 12:57.000 And every driver does it a bit different. 12:57.000 --> 13:03.000 That's a bit cumbersome if you want to hack it because every display has another driver inside. 13:03.000 --> 13:09.000 And sometimes they have eight groups and sometimes they have only five groups and sometimes the groups are, 13:09.000 --> 13:17.000 you know, ordered way, but you see the general thing is you have like a face air and B. 13:17.000 --> 13:21.000 And you can repeat this several times. 13:21.000 --> 13:24.000 And then you have another two place you can repeat this. 13:24.000 --> 13:27.000 And then you have a repeat counter for the whole block. 13:27.000 --> 13:30.000 And then you have 10 blocks of these. 13:30.000 --> 13:38.000 And so you can describe the voltage form you need to for your display. 13:38.000 --> 13:44.000 So that's another, that's the same thing like before. 13:44.000 --> 13:49.000 And that's the way it's in the storage of the driver. 13:49.000 --> 13:55.000 So you have the first thing is how many times the first block has to be repeated. 13:55.000 --> 13:58.000 Then you have the A and the B and the C in the D block. 13:58.000 --> 14:06.000 And if you can repeat them five times or four times, however you want. 14:06.000 --> 14:16.000 So usually that's kind of code for black white and two gray scales. 14:16.000 --> 14:22.000 It looks like this. And then I wrote some small program that makes the. 14:22.000 --> 14:29.000 So that's the curves that are coming to the to the pixels or the first thing is. 14:29.000 --> 14:34.000 I think it's white and then two gray scales and the black one here. 14:34.000 --> 14:39.000 That's the voltage that are going to the display for one display update. 14:39.000 --> 14:45.000 And then I wrote some small simulator what is means for the display pixel. 14:46.000 --> 14:58.000 And you see here you have the yellow line that's the position or the position I think the particles have just for the white particles. 14:58.000 --> 15:04.000 And you see on the first line the white particles are on the backside. 15:04.000 --> 15:12.000 And then in the middle lines you have two different height and on the last line the white particles are on the top. 15:12.000 --> 15:17.000 And what you also see is the green line the green line is the DC offset. 15:17.000 --> 15:27.000 So one thing is you should never put a long time one polarity on the display because then it will burn in and it will break. 15:27.000 --> 15:35.000 And you see on all this curves on the end of the curve the green line is again to zero. 15:35.000 --> 15:41.000 So if you add all the voltages up over one update, it should always be zero. 15:41.000 --> 15:51.000 So that's also the cause that in most of the time you see inverse picture displayed before and then it's featured to the right display. 15:51.000 --> 16:01.000 So that's the easiest way to accomplish the DC balance because if you always doing like this then you always have DC balance. 16:01.000 --> 16:13.000 If you do like partial updates or fast updates or want to display videos on this then you can also don't do this and just balance over the next pixel. 16:13.000 --> 16:27.000 If you know the last writing of the pixel is white then I can go directly to black I should only not white black the second time. 16:27.000 --> 16:39.000 Yes and what I have done as a demo for here is I take a normal e paper display that only has one or two bits per pixel. 16:39.000 --> 16:45.000 And can only display pictures like the above pixel. 16:45.000 --> 17:01.000 I modified the look so that the look up table so that I can have 16 or 32 device scales and I'm doing this by modifying the look the look up table during the update of the display. 17:01.000 --> 17:13.000 So in the first low I white black and white picture on the display where only the real black pixels are black and all the other pixels are white. 17:13.000 --> 17:29.000 And then I modified the look to display the darkest way and then I sending the picture the all the pixels that are have the darkest way and so on for everything I also have a small video here. 17:29.000 --> 17:43.000 So you see that's the update in the first time it it whites the and then on on this side you see a gray scale. 17:43.000 --> 17:55.000 So it's like a debug thing is and then in the end you have for all the gray scales you can after the talk you can see it in real life it looks much better than under. 17:55.000 --> 18:05.000 Yeah. So what's next? It's still missing the temperature or I'm starting to experiment with it. 18:05.000 --> 18:18.000 So I make some test screens where I write this kind of blocks with four volt with eight volt with nine volt with 17 volt and with different different lengths. 18:18.000 --> 18:33.000 So I can see on 60 volt I get a black nearly on seven and and 20 volt I need a bit more and on 10 volt you even need 60 frames until it gets real black. 18:33.000 --> 18:45.000 So with this kind of data I can modify and accomplish that picture stays the same even if the temperature is changing. 18:46.000 --> 19:01.000 Yeah, what could also be done or what I hope I can do is compress it so in theory I have two bits per pixel so I can write three gray scales per update so it gets faster. 19:01.000 --> 19:13.000 And if that can be done it can also be extended to multicolored paper I've already started to experiment with it but maybe next year. 19:13.000 --> 19:20.000 Yeah, so what what you have to take into account if you do your own load experiments. 19:20.000 --> 19:45.000 Yeah, don't forget there's one setting I don't mention it's the VCOM DC setting because of the TFT backplane the voltage on the on the backside needs to have a kind of offset because all the transistors they're eating a way a bit of voltage so the voltage on the backplane has to be a bit different. 19:45.000 --> 20:03.000 And the voltage on the front side has to don't have DC setting and this DC this voltage is depending on the panel and sometimes it's a problem because the manufacturer don't tell it and on some drivers you cannot read it but there are some tricks you can measure it. 20:04.000 --> 20:26.000 If you have a waveform where you have the same waveform on the front and on the on one of the pixels you can see if the pixel is changing then your DC offset is for and then you can search it and newer drivers they also have a function inside very automatically finds the DC offset. 20:26.000 --> 20:40.000 Yeah, so yes you should avoid permanent DC offset otherwise you burn your displays and yes maybe we can collect more more. 20:40.000 --> 20:52.000 Look up looks and waveform tables together and form an open source knowledge base for driving this kind of displays. 20:52.000 --> 20:58.000 Thank you. 20:59.000 --> 21:06.000 The five years for questions. 21:06.000 --> 21:08.000 Yeah. 21:08.000 --> 21:11.000 Have you tried out the burning in the display? 21:11.000 --> 21:16.000 Yes, it's you can get burned in in about. 21:17.000 --> 21:32.000 The question was if I tried to burn in the display? Yes, it's quite easy I think after 10 minutes for getting to switch off some voltages you can have burn in and it doesn't go away anymore. 21:33.000 --> 21:42.000 How does the the supply chain look for these displays? Is it like one company that or is it one company that makes this place? 21:42.000 --> 21:50.000 And then the other company makes the drivers and the DC integrates it with a display or how does it and which is the biggest one's. 21:50.000 --> 21:56.000 The question is how is the supply chain for the displays? The actual supply chain is that. 21:56.000 --> 22:02.000 Patent holder E ink is manufacturing the foil. 22:02.000 --> 22:17.000 Then you have companies like BOE that are great manufacturers for TFT screens they they're making the TFT back planes and then you have many model factories they combine this to and you have indeed. 22:18.000 --> 22:22.000 Around five or six manufacturers of driver ICs. 22:22.000 --> 22:28.000 But most of the time they are doing this together with E ink. 22:28.000 --> 22:38.000 And there's only one single left company that avoiding the patent of E ink and has a slightly different. 22:39.000 --> 22:48.000 And maybe it will go in the next years because the first E ink patents are no. 22:48.000 --> 22:52.000 Not more valid and expiring and. 22:53.000 --> 23:06.000 The question is if I tried to use waveforms to reduce energy. 23:06.000 --> 23:13.000 The question is if I tried to use waveforms to reduce the energy consumption. 23:13.000 --> 23:21.000 Yes, that was the first thing I have done for commercial project. 23:21.000 --> 23:27.000 It was the trade-off is you shouldn't use gray scales. 23:27.000 --> 23:32.000 And most of the time it's about to get the update faster. 23:32.000 --> 23:36.000 So you can go to sleep faster. 23:37.000 --> 23:44.000 You can do a bit the the integrated voltage generator usually is not that performant. 23:44.000 --> 23:51.000 You can optimize it a bit with a bit better coil and this kind of stuff. 23:52.000 --> 24:01.000 But why aren't the manufacturers doing that directly. 24:01.000 --> 24:09.000 Because the question is why the manufacturer don't do this in the first time. 24:09.000 --> 24:13.000 I think most of the. 24:14.000 --> 24:21.000 This place that you will get and not that optimized there just optimized for it's good enough. 24:21.000 --> 24:28.000 And if you buy five millions of this this place then they will talk it you and then they will optimize it. 24:28.000 --> 24:34.000 It's the same if you want to have fast update then I always have this kind of things. 24:34.000 --> 24:41.000 How maybe you you can set it to 150 degrees external temperature. 24:41.000 --> 24:52.000 And then we have a we have a hidden look up table inside for 150 degrees and then there there is some magic inside but we cannot help you with this. 24:52.000 --> 24:54.000 So that's most of the time. 24:54.000 --> 25:03.000 And I have to feeling that if you are big enough then they're talking directly to it and if you're small enough then you just get. 25:03.000 --> 25:09.000 Good enough this place. 25:09.000 --> 25:11.000 So what. 25:11.000 --> 25:17.000 How many different types of displays and if you try that you are you limited to like a couple of different. 25:17.000 --> 25:26.000 Manufacturers or do you do like nice format one sort of as a refurbished king or displays or anything like that. 25:26.000 --> 25:33.000 The question is how many different displays I have tried. 25:33.000 --> 25:47.000 Yeah I've for for the gray scales I only have this one because it was my my project to try to make like a photo booth. 25:48.000 --> 25:56.000 Most of my displays are coming from one company that has to do something that I. 25:56.000 --> 26:08.000 Working for display company and that's our big supplier for this place and so I'm trying to understand how they work because they don't understand it they just sell it to us. 26:08.000 --> 26:13.000 Yes. 26:13.000 --> 26:16.000 Thank you.