WEBVTT - Getting in Touch with Touchscreens 0:00:04.440 --> 0:00:12.639 Welcome to tech Stuff, a production from iHeartRadio. Hey there, 0:00:12.680 --> 0:00:16.320 and welcome to tech Stuff. I'm your host, Jonathan Strickland. 0:00:16.360 --> 0:00:19.040 I'm an executive producer with iHeartRadio. And how the tech 0:00:19.120 --> 0:00:23.520 are you. Let's talk a bit about touch screens. So 0:00:23.600 --> 0:00:27.240 in the grand scheme of things, they're a fairly recent invention. 0:00:27.800 --> 0:00:31.160 If you look back at the original Star Trek series, 0:00:31.560 --> 0:00:35.040 you can see that they are a recent invention because 0:00:35.760 --> 0:00:38.800 they didn't think about touch screens when they were designing 0:00:38.840 --> 0:00:42.240 the sets for Star Trek. The Enterprise, which is the 0:00:42.280 --> 0:00:47.239 flagship of the Federation, used physical buttons and switches, not 0:00:47.400 --> 0:00:50.280 touch screens. Now, that should not come as a surprise. 0:00:50.760 --> 0:00:54.520 The set designers were taking their inspiration from electronic devices 0:00:54.560 --> 0:00:57.960 and mainframe computers of the time and then just saying, 0:00:57.960 --> 0:01:02.080 how can we make that look more futury? And you 0:01:02.120 --> 0:01:04.280 can't blame them for failing to predict that in the 0:01:04.319 --> 0:01:08.319 future people would interact with technologies through other means, including 0:01:08.600 --> 0:01:11.760 voice and touch. By the time we get up to 0:01:11.800 --> 0:01:15.479 Star Trek the next generation, things had changed quite a bit. 0:01:15.920 --> 0:01:18.680 The controls on the new Enterprise were these sort of 0:01:18.720 --> 0:01:22.480 touch sensitive panels. They had control surfaces that were built 0:01:22.480 --> 0:01:26.160 directly into walls and consoles in such a way that 0:01:26.200 --> 0:01:28.120 I bet it was someone's full time gig on the 0:01:28.200 --> 0:01:30.360 set to just wipe down the surfaces to get rid 0:01:30.400 --> 0:01:34.640 of all the smudges. They also had voice commands built 0:01:34.640 --> 0:01:36.920 into their computer system at that point, so that was 0:01:37.280 --> 0:01:40.880 pretty cool too. They kind of had both of those 0:01:42.319 --> 0:01:46.640 blossoming technologies involved in Star Trek next generation. And there 0:01:46.680 --> 0:01:49.800 are actually several different methods that you could follow to 0:01:49.840 --> 0:01:53.840 create a touch screen or touch surface. So for example, 0:01:54.720 --> 0:01:59.600 you could have a rear projection screen and you're projecting 0:01:59.640 --> 0:02:02.920 image is from behind the screen onto the screen, and 0:02:03.040 --> 0:02:06.960 also behind the screen, you could have a bunch of 0:02:07.360 --> 0:02:11.320 near infrared cameras, and these near infrared cameras could detect 0:02:11.639 --> 0:02:16.280 when a fingertip or some object makes contact with the 0:02:16.440 --> 0:02:21.280 surface that's on the other side and then map that 0:02:21.800 --> 0:02:26.560 to a program that creates the appropriate response. The original 0:02:26.720 --> 0:02:31.320 Microsoft surface, which later would be called the Pixel Sense, 0:02:31.600 --> 0:02:36.240 had something like this and used multiple near infrared cameras 0:02:36.280 --> 0:02:39.840 I think five of them behind the screen to detect 0:02:39.840 --> 0:02:43.960 and track objects that make contact with the screen. If 0:02:43.960 --> 0:02:46.120 you don't recall, the pixel Sense had sort of a 0:02:46.200 --> 0:02:50.880 table form factor. It was quite a large display, bigger 0:02:50.919 --> 0:02:53.440 than what you would have with like a tablet. But 0:02:54.000 --> 0:02:56.560 I wanted to talk about the differences between the two 0:02:57.080 --> 0:03:02.360 most common touchscreen technologies that consumers typically encounter. So first 0:03:02.440 --> 0:03:06.320 up is actually capacitive touch. This is really the type 0:03:06.360 --> 0:03:10.160 of screen you're most likely to encounter these days. Most 0:03:10.160 --> 0:03:14.720 touch screen technology falls back on this, and capacitive touch 0:03:14.800 --> 0:03:18.799 predates the other technology that we'll talk about by about 0:03:18.840 --> 0:03:22.880 five years or so. So back in nineteen sixty five, 0:03:23.000 --> 0:03:27.560 there was a British engineer named E. A. Johnson who 0:03:27.600 --> 0:03:32.600 developed capasitive touch technologies while working for the Royal Radar Establishment. 0:03:33.120 --> 0:03:35.280 He wrote up his work in a paper he titled 0:03:35.440 --> 0:03:40.760 Touch Displays a Programmed Man Machine Interface in nineteen sixty seven. 0:03:41.600 --> 0:03:46.680 A capacitive screen consists of several layers, So we're going 0:03:46.760 --> 0:03:50.160 to work from the bottom up, and by up, I 0:03:50.200 --> 0:03:52.360 mean like at the top layer will be the surface 0:03:52.360 --> 0:03:56.320 that you would interact with. So at the base you 0:03:56.360 --> 0:03:59.800 have your actual display, right, this is what is generating 0:03:59.800 --> 0:04:03.280 the image that you're going to see through the other layers. 0:04:03.640 --> 0:04:05.520 So all the layers on top of this need to 0:04:05.520 --> 0:04:08.000 be transparent, because otherwise you wouldn't be able to see 0:04:08.000 --> 0:04:10.840 the stuff that's on the display, and you've kind of 0:04:10.880 --> 0:04:14.760 eliminated the purposes of having a touchscreen device. Now, typically 0:04:15.080 --> 0:04:18.400 you would have a thin glass substrate that would be 0:04:18.440 --> 0:04:21.719 on top of the display, and then the next layer 0:04:21.800 --> 0:04:25.480 up would be a conductive layer. So this is a 0:04:25.560 --> 0:04:30.000 layer that creates an electrostatic field across it. On top 0:04:30.040 --> 0:04:35.960 of that layer is a thin transparent layer, and this 0:04:36.040 --> 0:04:41.120 is the layer that you could actually touch. So if 0:04:41.160 --> 0:04:46.839 something conductive makes contact with this top layer, then some 0:04:47.080 --> 0:04:50.760 of the electrostatic charge on the layer beneath the top 0:04:50.839 --> 0:04:54.159 layer will transfer to that conductive material. So let's just 0:04:54.160 --> 0:04:57.800 say it's your finger. Make it easy. So you touch 0:04:57.839 --> 0:05:01.560 your finger to the surface of a screen. Your finger 0:05:01.720 --> 0:05:06.479 is conductive, and once you touch the screen, some of 0:05:06.560 --> 0:05:11.599 the charge on the surface underneath that top layer transfers 0:05:11.640 --> 0:05:15.000 to your finger, and the charge decreases at the point 0:05:15.040 --> 0:05:18.520 of contact. So you've got circuits that are built into 0:05:18.560 --> 0:05:21.640 the edge of the screen, often at the corners, and 0:05:21.680 --> 0:05:26.120 they detect where precisely that charge decrease in the capacitive 0:05:26.200 --> 0:05:30.560 layer happens and registers this as a contact and then 0:05:30.600 --> 0:05:33.120 that translates into an action based on whatever it is 0:05:33.160 --> 0:05:36.120 you're doing so. Like if you're playing a game and 0:05:36.160 --> 0:05:39.240 you move your finger across the screen, it says, all right, well, 0:05:39.400 --> 0:05:42.360 the point of contact started at this position, it ended 0:05:42.400 --> 0:05:45.360 at that position, and that means we need to reflect 0:05:45.400 --> 0:05:48.760 that in moving a character from one point to another 0:05:48.880 --> 0:05:52.400 or whatever it may be. Now, this is why if 0:05:52.400 --> 0:05:56.520 you're wearing non conductive gloves, you can't interact with a 0:05:56.560 --> 0:06:00.360 touch screen, a capacitive touch screen properly, unless you, you know, 0:06:00.440 --> 0:06:04.400 carry around something like a hot dog around that would work. 0:06:04.839 --> 0:06:07.440 I've actually seen people or pictures of people in Japan 0:06:07.520 --> 0:06:11.320 doing that when the weather was really darn cold. Hot 0:06:11.320 --> 0:06:15.560 dog phone. But also like anything that hasity, a conductive 0:06:15.640 --> 0:06:19.720 rather a conductive surface would work. It's just that if 0:06:19.720 --> 0:06:23.040 you're wearing gloves that insulate you, then that doesn't work. 0:06:23.080 --> 0:06:27.560 That's why some gloves come with a little conductive mesh 0:06:27.839 --> 0:06:29.960 at the fingertips so that you can still interact with 0:06:30.000 --> 0:06:34.599 your capacitive touch screen devices while wearing the gloves. Now, 0:06:35.560 --> 0:06:39.800 the version that Johnson invented way back in nineteen sixty 0:06:39.880 --> 0:06:44.720 five was understandably limited. It could only detect the presence 0:06:44.839 --> 0:06:47.159 of a touch. It couldn't tell the difference between one 0:06:47.200 --> 0:06:50.800 finger or two fingers or anything like that. I don't 0:06:50.839 --> 0:06:54.400 think it could even detect where on the screen the 0:06:54.440 --> 0:06:58.640 touch happened, just that there was a touch. So in 0:06:58.680 --> 0:07:00.720 other words, it was kind of an on off or 0:07:00.800 --> 0:07:04.560 binary system. Either something conductive was in contact with the 0:07:04.560 --> 0:07:08.320 screen or it wasn't. But this served as the foundation 0:07:08.440 --> 0:07:11.680 for the capacitive touch screens we used today. The problem 0:07:11.760 --> 0:07:17.480 is they were expensive, so while it was possible, it 0:07:17.520 --> 0:07:23.000 didn't really proliferate because the use cases were fairly limited, 0:07:23.520 --> 0:07:25.840 and it didn't make any sense to try and incorporate 0:07:25.880 --> 0:07:29.600 that into consumer technology because whatever you made would be 0:07:29.680 --> 0:07:35.200 way too expensive. The other common touch screen technology is 0:07:35.240 --> 0:07:39.840 called resistive touch. In nineteen seventy, an inventor named G. 0:07:40.240 --> 0:07:42.680 Samuel Hurst was trying to figure out a way to 0:07:42.800 --> 0:07:46.560 more efficiently make use of a vandograph accelerator, and so 0:07:46.680 --> 0:07:51.240 he came up with the idea of using electrically conductive paper. Essentially, 0:07:51.320 --> 0:07:56.520 these papers would have like a grid along the X 0:07:56.560 --> 0:08:01.600 and y axis of the paper, and you could detect 0:08:01.840 --> 0:08:06.480 a change in voltage along those grids, so you could 0:08:06.520 --> 0:08:09.720 you could plot a specific point of contact by the 0:08:09.720 --> 0:08:13.640 way a vandograph generator, you know, a vandograph accelerator is 0:08:13.680 --> 0:08:17.520 what Hearst was referring to, but that's because a vandograph 0:08:17.640 --> 0:08:21.920 generator was used as a very primitive particle accelerator back 0:08:21.920 --> 0:08:25.880 in the day. It is an electrostatic generator. You've probably 0:08:26.160 --> 0:08:28.480 at least seen pictures of these, if not actually seen 0:08:28.480 --> 0:08:33.880 one in use. So typically you're using a belt mounted 0:08:34.080 --> 0:08:38.200 on some rollers that turn very quickly. This makes the 0:08:38.200 --> 0:08:42.880 belt move very quickly, and the moving belt actually typically 0:08:42.920 --> 0:08:46.800 makes contact with another surface, but it generates this electrostatic 0:08:46.880 --> 0:08:52.680 charge and carries that charge to a hollow metal globe. 0:08:53.040 --> 0:08:56.800 The globe itself is also mounted on top of a 0:08:56.920 --> 0:08:59.720 column that's made of some sort of insulator material, so 0:08:59.760 --> 0:09:03.520 this isolates the metal globe. Right, You're building up this 0:09:03.600 --> 0:09:06.719 electrostatic charge in the metal globe and there's nowhere for 0:09:06.760 --> 0:09:11.400 the charge to go because you've isolated the globe. And 0:09:11.440 --> 0:09:16.600 then you can bring something conductive in you know, general 0:09:16.640 --> 0:09:20.200 proximity of the globe, and as you get close enough, 0:09:20.800 --> 0:09:26.640 the difference in electric potentials will cause a spark to form. 0:09:27.160 --> 0:09:30.959 Like you essentially create a circuit very very briefly, and 0:09:31.000 --> 0:09:34.920 then you get this zap of a spark and you've 0:09:34.960 --> 0:09:37.720 probably seen, like I said, one of these, either in 0:09:37.840 --> 0:09:40.600 video or maybe even in person. You're likely to find 0:09:40.640 --> 0:09:43.400 it in like science classrooms to help demonstrate the principles 0:09:43.400 --> 0:09:46.600 of electrostatics. But back in the day they were used 0:09:46.600 --> 0:09:51.560 as particle accelerators in physics research. Yes, today it's a 0:09:51.640 --> 0:09:54.000 toy and a science classroom, but back in the day, 0:09:54.440 --> 0:09:57.400 it was a particle accelerator. Anyway, doctor Hurst used the 0:09:57.760 --> 0:10:01.480 electrically conductive paper to plot charge on X and y axis, 0:10:02.000 --> 0:10:04.000 and only a bit later did he realize that what 0:10:04.120 --> 0:10:08.960 he was doing could potentially have other applications outside the lab. 0:10:09.640 --> 0:10:12.600 I'll explain more, but first let's take a quick break. 0:10:22.120 --> 0:10:25.040 So doctor Hurst and his team figured that they might 0:10:25.120 --> 0:10:31.640 actually have some applications for this conductive paper beyond the 0:10:31.679 --> 0:10:37.240 plotting of charges using a vandograph accelerator. And he thought 0:10:37.280 --> 0:10:41.760 that he could make this into a touchscreen interface. So 0:10:42.559 --> 0:10:46.440 this would be a resistive touch screen. They actually have 0:10:46.520 --> 0:10:49.600 more layers than capacitive touch screens. That also means they 0:10:49.640 --> 0:10:53.360 block a little more light than capacitive touch screens do, 0:10:53.520 --> 0:10:57.800 so resistive screens tend to be dimmer than capacitive ones. 0:10:58.360 --> 0:11:00.559 So let's go through those layers again and again, we're 0:11:00.600 --> 0:11:03.360 going to start from the display side up to the 0:11:03.440 --> 0:11:07.160 surface where you would make contact with the screen. So 0:11:07.240 --> 0:11:09.560 at the very base you've still got your display, just 0:11:09.600 --> 0:11:13.280 like with capacitive. On top of the display, you've got 0:11:13.280 --> 0:11:18.400 a glass substrate. Above that you have a transparent conductive layer, 0:11:18.800 --> 0:11:20.560 so again similar to what you would have with the 0:11:20.559 --> 0:11:24.360 capacitive screen. But next you would have a layer of 0:11:24.400 --> 0:11:27.959 what are called separator dots. So these are our little 0:11:27.960 --> 0:11:33.720 supports that are non conductive. They are there to act 0:11:34.040 --> 0:11:39.920 as a separator. They keep the first transparent conductive layer 0:11:40.240 --> 0:11:45.320 separate from a second transparent conductive layer, so they're there 0:11:45.360 --> 0:11:50.240 to keep space between those two layers. So again above 0:11:50.320 --> 0:11:55.000 these separator dots is that second transparent conductive layer, and 0:11:55.040 --> 0:11:58.559 then on the very top you have a flexible transparent 0:11:58.679 --> 0:12:02.120 film on top. This is where you would make contact 0:12:02.120 --> 0:12:06.800 with the screen. So when you push down on the screen, 0:12:06.880 --> 0:12:10.840 whether it's with a conductive surface or not, what you're 0:12:10.840 --> 0:12:16.800 doing is you're deforming the top most transparent layer to 0:12:16.840 --> 0:12:20.360 push down and come into contact with the next transparent 0:12:20.400 --> 0:12:25.880 conductive layer. That creates a circuit. So as long as 0:12:25.920 --> 0:12:29.000 you're pushing down with enough force, you're creating the circuit 0:12:29.080 --> 0:12:34.080 and it will detect that touch. So typically you've got 0:12:35.120 --> 0:12:38.679 other circuits in the device that detect drops in voltage 0:12:38.720 --> 0:12:42.160 or changes in voltage, and that's how they can detect 0:12:42.480 --> 0:12:47.000 the precise location where the touch happened. So again, doesn't 0:12:47.000 --> 0:12:50.320 matter if it's your finger, if you're wearing gloves, if 0:12:50.360 --> 0:12:55.160 you're using a stylus, it doesn't really matter. What matters 0:12:55.200 --> 0:12:59.200 is that that top transparent conductive layer comes into contact 0:12:59.200 --> 0:13:02.800 with the bottom transparent conductive layer and creates a circuit. 0:13:03.400 --> 0:13:07.440 So the capacitive screen actually came first, but the resistive 0:13:07.480 --> 0:13:11.320 screen was more popular. It got more popular, and it 0:13:11.480 --> 0:13:15.360 did so faster than capacitive. So why is that, Well, 0:13:16.400 --> 0:13:19.920 mostly it comes down to cost. Also, like the fact 0:13:19.920 --> 0:13:22.640 that you didn't have to have a conductive material to 0:13:22.800 --> 0:13:25.520 work with it meant that you could actually use it 0:13:25.559 --> 0:13:28.199 for lots of other stuff, including stuff where you might 0:13:28.280 --> 0:13:30.600 have to do something like wear gloves, but you could 0:13:30.679 --> 0:13:34.840 use a stylus like That's a useful part of that 0:13:34.880 --> 0:13:37.360 technology is the fact that you can still work with 0:13:37.400 --> 0:13:40.600 it even if you aren't able to, you know, use 0:13:40.640 --> 0:13:43.920 your fingers directly on the screen. But it was much 0:13:44.000 --> 0:13:47.040 cheaper and that was really the big thing, so capacitive 0:13:47.800 --> 0:13:49.800 sort of took a back seat for a while, and 0:13:50.040 --> 0:13:52.680 it would require a lot more innovation in the space 0:13:52.760 --> 0:13:56.960 to make capacitive screens more attractive than resistive screens. However, 0:13:57.080 --> 0:14:00.040 these days, most consumer devices you're going to come in 0:14:00.080 --> 0:14:05.520 to contact with use capacitive touch screens, largely because, I mean, 0:14:05.520 --> 0:14:08.560 they're still more expensive than resistive touch screens, but they 0:14:08.600 --> 0:14:13.760 can display brighter images, so that's definitely a positive. They 0:14:13.840 --> 0:14:15.920 tend to be more durable as well as you can 0:14:15.960 --> 0:14:19.040 imagine if you've got a resistive touch screen, which is 0:14:19.560 --> 0:14:22.720 it works based upon you pushing the screen hard enough 0:14:22.760 --> 0:14:25.520 to make contact between two layers. I mean, you don't 0:14:25.520 --> 0:14:27.680 have to push super hard, but it does have to 0:14:27.680 --> 0:14:32.840 be enough pressure so that the system detects there's a 0:14:32.880 --> 0:14:37.480 touch there. Well, as you might imagine, this eventually deforms 0:14:38.200 --> 0:14:42.960 the upper transparent conductive layer, and that you can eventually 0:14:43.000 --> 0:14:46.400 get to points where it's already close to or making 0:14:46.440 --> 0:14:48.840 contact with the lower layer. Just kind of like having 0:14:48.840 --> 0:14:52.600 a short circuit, right, and it makes it more difficult 0:14:53.120 --> 0:14:58.480 to have an accurate experience. Using resistive touch screens. Doesn't 0:14:58.480 --> 0:15:02.800 happen overnight, but over time it does happen, So that's 0:15:02.840 --> 0:15:06.760 one of the other benefits capacitive touch screens have over resistive. 0:15:07.720 --> 0:15:11.360 It's also easier to use capacitive touch screens for multi 0:15:11.400 --> 0:15:15.600 touch functions in general, not that you couldn't do it 0:15:15.640 --> 0:15:18.400 with resistive touch screens, but it's just it's easier when 0:15:18.440 --> 0:15:22.560 you're not focusing on using pressure to make that point 0:15:22.560 --> 0:15:26.440 of contact. You will still find resistive touch screens, however, 0:15:26.680 --> 0:15:30.040 in devices that are aimed at lower price points, So 0:15:30.360 --> 0:15:33.200 if you're looking at like a budget tablet, there are 0:15:33.200 --> 0:15:36.680 a lot of industrial uses for resistive touch screens to 0:15:36.760 --> 0:15:40.080 this day. And keep in mind, as I said at 0:15:40.120 --> 0:15:42.680 the beginning of this episode, there are other types of 0:15:42.720 --> 0:15:47.160 touch screen technologies besides these two. There's some that use acoustics, 0:15:47.320 --> 0:15:51.160 there's some that use infrared lasers. Like I said with 0:15:51.240 --> 0:15:53.560 the surface, there are the kinds that use you know, 0:15:54.200 --> 0:15:57.720 cameras that are mounted behind the screen itself. It's not 0:15:57.880 --> 0:16:00.520 like these two are the only two. There are lots 0:16:00.520 --> 0:16:02.840 of other technologies. It's just those two are the ones 0:16:02.880 --> 0:16:06.880 you're most likely to come into contact with, both figuratively 0:16:07.160 --> 0:16:12.120 and literally. So I hope that this was interesting and informative. 0:16:13.080 --> 0:16:16.520 A little tech Stuff Tidbits episode, and I'm trying to 0:16:16.720 --> 0:16:19.400 do more of these because it's fun to do these 0:16:19.440 --> 0:16:22.600 short ones. It's just a challenge because you know, I'm 0:16:22.600 --> 0:16:24.920 a chatty Kathy. This episode probably could have been eight 0:16:24.920 --> 0:16:27.520 minutes long and instead of going twice as long. So 0:16:28.400 --> 0:16:31.560 but hey, I like your company, hope you like mine, 0:16:32.200 --> 0:16:34.720 And if you have any suggestions for little things that 0:16:34.760 --> 0:16:37.800 you would like explained in the tech space, even if 0:16:37.800 --> 0:16:40.040 it's something like, hey, can you give a quick rundown 0:16:40.080 --> 0:16:43.240 on logic gates and what those do or something along 0:16:43.280 --> 0:16:45.960 those lines, let me know and I'll look into it. 0:16:46.440 --> 0:16:49.480 And I hope you are all well, and I'll talk 0:16:49.520 --> 0:16:59.760 to you again really soon. Tech Stuff is an iHeartRadio production. 0:17:00.080 --> 0:17:05.080 For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, 0:17:05.200 --> 0:17:07.200 or wherever you listen to your favorite shows.