WEBVTT - Rerun: Getting in Touch with Touchscreens 0:00:04.440 --> 0:00:09.039 Welcome to Tech Stuff, a production from iHeartRadio. 0:00:11.920 --> 0:00:12.640 Hey there, and. 0:00:12.560 --> 0:00:16.120 Welcome to tech Stuff. I'm your host, Jonathan Strickland. I'm 0:00:16.160 --> 0:00:20.160 an executive producer with iHeart Podcasts and how the tech 0:00:20.200 --> 0:00:23.640 are you? So I'm still on vacation and that means 0:00:23.680 --> 0:00:25.760 that we're going to listen to an episode that originally 0:00:25.760 --> 0:00:29.240 published on May thirty first, twenty twenty three. It is 0:00:29.320 --> 0:00:33.720 titled Getting in Touch with touch Screens. So, yeah, we 0:00:33.800 --> 0:00:36.960 talk all about the touch screen technology and the two 0:00:37.520 --> 0:00:41.040 well there's more than two, but the two major ways 0:00:41.400 --> 0:00:43.960 touch screen technology tends to work. 0:00:44.560 --> 0:00:44.920 Enjoy. 0:00:48.440 --> 0:00:52.000 Let's talk a bit about touch screens. So, in the 0:00:52.000 --> 0:00:56.200 grand scheme of things, they're a fairly recent invention. If 0:00:56.200 --> 0:00:59.720 you look back at the original Star Trek series, you 0:00:59.800 --> 0:01:04.120 can see that they are a recent invention because they 0:01:04.120 --> 0:01:08.160 didn't think about touch screens when they were designing the sets. 0:01:07.880 --> 0:01:08.560 For Star Trek. 0:01:08.680 --> 0:01:13.360 The Enterprise, which is the flagship of the Federation, used 0:01:13.480 --> 0:01:17.400 physical buttons and switches, not touch screens. Now that should 0:01:17.440 --> 0:01:20.240 not come as a surprise. The set designers were taking 0:01:20.280 --> 0:01:24.480 their inspiration from electronic devices and mainframe computers of the 0:01:24.600 --> 0:01:27.080 time and then just saying how can we make that 0:01:27.160 --> 0:01:31.720 look more futury, and you can't blame them for failing 0:01:31.760 --> 0:01:33.840 to predict that in the future people would interact with 0:01:33.880 --> 0:01:39.280 technologies through other means, including voice and touch. By the 0:01:39.280 --> 0:01:41.320 time we get up to Star Trek the next Generation, 0:01:42.360 --> 0:01:43.400 things had changed. 0:01:43.200 --> 0:01:43.679 Quite a bit. 0:01:44.120 --> 0:01:46.880 The controls on the New Enterprise were these sort of 0:01:46.920 --> 0:01:50.680 touch sensitive panels. They had control surfaces that were built 0:01:50.680 --> 0:01:54.360 directly into walls and consoles in such a way that 0:01:54.400 --> 0:01:56.320 I bet it was someone's full time gig on the 0:01:56.400 --> 0:01:58.560 set to just wipe down the surfaces to get rid 0:01:58.600 --> 0:02:02.840 of all the smudges. They also had voice commands built 0:02:02.880 --> 0:02:05.120 into their computer system at that point, so that was 0:02:05.480 --> 0:02:09.080 pretty cool too. They kind of had both of those 0:02:10.520 --> 0:02:14.880 blossoming technologies involved in Star Trek Next Generation. And there 0:02:14.880 --> 0:02:18.000 are actually several different methods that you could follow to 0:02:18.040 --> 0:02:22.040 create a touch screen or touch surface. So, for example, 0:02:22.919 --> 0:02:27.840 you could have a rear projection screen and you're projecting 0:02:27.919 --> 0:02:31.480 images from behind the screen onto the screen. And also 0:02:31.600 --> 0:02:35.800 behind the screen, you could have a bunch of near 0:02:35.880 --> 0:02:40.080 infrared cameras, and these near infrared cameras could detect when 0:02:40.120 --> 0:02:45.079 a fingertip or some object makes contact with the surface 0:02:45.520 --> 0:02:50.080 that's on the other side and then map that to 0:02:50.200 --> 0:02:56.200 a program that creates the appropriate response. The original Microsoft Surface, 0:02:56.360 --> 0:03:00.680 which later would be called the Pixel Sense, had something 0:03:00.760 --> 0:03:04.760 like this and used multiple near infrared cameras I think 0:03:04.919 --> 0:03:08.480 five of them behind the screen to detect and track 0:03:08.600 --> 0:03:12.760 objects that make contact with the screen. If you don't recall, 0:03:12.800 --> 0:03:16.080 the pixel Sense had sort of a table form factor. 0:03:16.760 --> 0:03:19.480 It was quite a large display, bigger than what you 0:03:19.480 --> 0:03:20.760 would have with like a tablet. 0:03:21.560 --> 0:03:22.799 But I wanted to. 0:03:22.720 --> 0:03:26.480 Talk about the differences between the two most common touch 0:03:26.480 --> 0:03:31.200 screen technologies that consumers typically encounter. So first up is 0:03:31.240 --> 0:03:35.000 actually capacitive touch. This is really the type of screen 0:03:35.200 --> 0:03:38.840 you're most likely to encounter these days. Most touch screen 0:03:38.880 --> 0:03:43.760 technology falls back on this, and capacitive touch predates the 0:03:43.880 --> 0:03:47.680 other technology that we'll talk about by about five years 0:03:47.800 --> 0:03:51.480 or so. So back in nineteen sixty five, there was 0:03:51.520 --> 0:03:56.720 a British engineer named E. A. Johnson who developed capasitive 0:03:56.760 --> 0:04:01.400 touch technologies while working for the Royal Radar Establishment. He 0:04:01.440 --> 0:04:03.920 wrote up his work in a paper he titled Touch 0:04:04.040 --> 0:04:08.960 Displays a Programmed Man Machine Interface in nineteen sixty seven. 0:04:09.800 --> 0:04:15.080 A capacitive screen consists of several layers, so we're gonna 0:04:15.080 --> 0:04:18.560 work from the bottom up, and by up, I mean 0:04:18.640 --> 0:04:20.680 like at the top layer will be the surface that 0:04:20.760 --> 0:04:24.640 you would interact with. So at the base you have 0:04:24.720 --> 0:04:28.200 your actual display. Right, this is what is generating the 0:04:28.240 --> 0:04:32.000 image that you're gonna see through the other layers. So 0:04:32.120 --> 0:04:33.800 all the layers on top of this need to be 0:04:33.839 --> 0:04:36.240 transparent because otherwise you wouldn't be able to see the 0:04:36.240 --> 0:04:39.640 stuff that's on the display, and you've kind of eliminated 0:04:39.680 --> 0:04:43.359 the purposes of having a touchscreen device. Now. Typically you 0:04:43.400 --> 0:04:46.760 would have a thin glass substrate that would be on 0:04:46.839 --> 0:04:50.279 top of the display, and then the next layer up 0:04:50.600 --> 0:04:54.039 would be a conductive layer. So this is a layer 0:04:54.040 --> 0:04:58.360 that creates an electrostatic field across it. On top of 0:04:58.400 --> 0:05:04.159 that layer is a a thin transparent layer, and this 0:05:04.240 --> 0:05:09.320 is the layer that you could actually touch. So if 0:05:09.360 --> 0:05:15.039 something conductive makes contact with this top layer, then some 0:05:15.279 --> 0:05:19.000 of the electrostatic charge on the layer beneath the top 0:05:19.040 --> 0:05:21.839 layer will transfer to that conductive material. 0:05:21.920 --> 0:05:23.839 So let's just say it's your finger. Make it easy. 0:05:24.360 --> 0:05:28.760 So you touch your finger to the surface of a screen. 0:05:29.200 --> 0:05:33.440 Your finger is conductive, and once you touch the screen, 0:05:34.200 --> 0:05:38.600 some of the charge on the surface underneath that top 0:05:38.640 --> 0:05:42.880 layer transfers to your finger, and the charge decreases at 0:05:42.880 --> 0:05:46.240 the point of contact. So you've got circuits that are 0:05:46.240 --> 0:05:49.400 built into the edge of the screen, often at the corners, 0:05:49.760 --> 0:05:53.760 and they detect where precisely that charge decrease in the 0:05:53.760 --> 0:05:58.560 capacitive layer happens and registers this as a contact and 0:05:58.600 --> 0:06:01.200 then that translates into an action based on whatever it 0:06:01.240 --> 0:06:01.839 is you're doing. 0:06:02.360 --> 0:06:03.720 So like if you're playing a. 0:06:03.640 --> 0:06:06.600 Game and you move your finger across the screen, it says, 0:06:06.600 --> 0:06:10.039 all right, well, the point of contact started at this position, 0:06:10.080 --> 0:06:12.880 it ended at that position, and that means we need 0:06:12.920 --> 0:06:16.440 to reflect that in moving a character from one point 0:06:16.480 --> 0:06:19.400 to another or whatever it may be. Now, this is 0:06:19.440 --> 0:06:24.440 why if you're wearing non conductive gloves, you can't interact 0:06:24.480 --> 0:06:28.040 with a touch screen, a capacitive touch screen properly unless 0:06:28.080 --> 0:06:32.080 you carry around something like a hot dog around that 0:06:32.120 --> 0:06:35.120 would work. I've actually seen people or pictures of people 0:06:35.160 --> 0:06:37.640 in Japan doing that when the weather was really darn cold. 0:06:38.320 --> 0:06:40.719 Hm hot dog phone. 0:06:40.839 --> 0:06:44.280 But also like anything that has a conductive rather a 0:06:44.320 --> 0:06:48.360 conductive surface would work. It's just that if you're wearing 0:06:48.360 --> 0:06:51.640 gloves that insulate you, then that doesn't work. That's why 0:06:51.680 --> 0:06:56.279 some gloves come with a little conductive mesh at the 0:06:56.279 --> 0:06:59.040 fingertips so that you can still interact with your capacitive 0:06:59.120 --> 0:07:03.880 touch screen device is while wearing the gloves. Now, the 0:07:04.000 --> 0:07:08.320 version that Johnson invented way back in nineteen sixty five 0:07:08.480 --> 0:07:13.120 was understandably limited. It could only detect the presence of 0:07:13.160 --> 0:07:15.760 a touch. It couldn't tell the difference between one finger 0:07:16.360 --> 0:07:19.160 or two fingers or anything like that. I don't think 0:07:19.200 --> 0:07:23.400 it could even detect where on the screen the touch happened, 0:07:23.600 --> 0:07:27.240 just that there was a touch. So, in other words, 0:07:27.280 --> 0:07:29.920 it was kind of an on off or binary system. 0:07:30.040 --> 0:07:33.840 Either something conductive was in contact with the screen or 0:07:33.880 --> 0:07:36.840 it wasn't. But this served as the foundation for the 0:07:36.880 --> 0:07:40.960 capacitive touch screens we use today. The problem is they 0:07:40.960 --> 0:07:46.680 were expensive, so while it was possible, it didn't really 0:07:46.800 --> 0:07:52.160 proliferate because the use cases were fairly limited, and it 0:07:52.200 --> 0:07:54.480 didn't make any sense to try and incorporate that into 0:07:54.520 --> 0:07:58.960 consumer technology because whatever you made would be way too expensive. 0:08:00.080 --> 0:08:04.800 The other common touch screen technology is called resistive touch. 0:08:05.360 --> 0:08:09.720 In nineteen seventy, an inventor named G. Samuel Hurst was 0:08:09.760 --> 0:08:11.960 trying to figure out a way to more efficiently make 0:08:12.080 --> 0:08:15.480 use of a vandograph accelerator, and so he came up 0:08:15.520 --> 0:08:18.640 with the idea of using electrically conductive paper. 0:08:19.080 --> 0:08:20.680 Essentially, these papers. 0:08:20.520 --> 0:08:24.720 Would have like a grid along the you know, X 0:08:24.760 --> 0:08:29.760 and y axis of the paper, and you could detect 0:08:30.040 --> 0:08:34.680 a change in voltage along those grids, so you could 0:08:34.720 --> 0:08:38.160 you could plot a specific point of contact. By the way, 0:08:38.400 --> 0:08:41.960 a vandograph generator, you know, a vandograph accelerator is what 0:08:43.160 --> 0:08:46.320 Hearst was referring to. But that's because a vandograph generator 0:08:46.400 --> 0:08:50.200 was used as a very primitive particle accelerator back in 0:08:50.240 --> 0:08:54.480 the day. It is an electrostatic generator. You've probably at 0:08:54.520 --> 0:08:56.920 least seen pictures of these, if not actually seen one 0:08:57.040 --> 0:09:02.360 in use. So typically you're using a belt mounted on 0:09:02.600 --> 0:09:06.720 some rollers that turn very quickly. This makes the belt 0:09:06.760 --> 0:09:11.360 move very quickly, and the moving belt actually typically makes 0:09:11.400 --> 0:09:15.400 contact with another surface, but it generates this electrostatic charge 0:09:15.840 --> 0:09:21.360 and carries that charge to a hollow metal globe. The 0:09:21.360 --> 0:09:25.679 globe itself is also mounted on top of a column 0:09:25.760 --> 0:09:28.080 that's made of some sort of insulator material, so this 0:09:29.160 --> 0:09:32.640 isolates the metal globe. Right, You're building up this electrostatic 0:09:32.760 --> 0:09:35.080 charge in the metal globe and there's nowhere for the 0:09:35.160 --> 0:09:39.800 charge to go because you've isolated the globe, and then 0:09:39.880 --> 0:09:45.400 you can bring something conductive in you know, general proximity 0:09:45.440 --> 0:09:49.360 of the globe, and as you get close enough, the 0:09:49.400 --> 0:09:54.839 difference in electric potentials will cause a spark to form. 0:09:55.360 --> 0:09:59.160 Like you essentially create a circuit very very briefly, and 0:09:59.200 --> 0:10:03.120 then you get this zap of a spark. And you've 0:10:03.160 --> 0:10:05.920 probably seen, like I said, one of these, either in 0:10:06.040 --> 0:10:08.800 video or maybe even in person. You're likely to find 0:10:08.840 --> 0:10:12.479 it in science classrooms to help demonstrate the principles of electrostatics. 0:10:12.920 --> 0:10:15.560 But back in the day they were used as particle 0:10:15.600 --> 0:10:20.160 accelerators in physics research. Yes, today it's a toy and 0:10:20.200 --> 0:10:22.839 a science classroom, but back in the day it was 0:10:22.880 --> 0:10:26.960 a particle accelerator. Anyway, Doctor Hurst used the electrically conductive 0:10:27.000 --> 0:10:30.280 paper to plot charges on X and y axis, and 0:10:30.360 --> 0:10:32.400 only a bit later did he realize that what he 0:10:32.520 --> 0:10:37.160 was doing could potentially have other applications outside the lab. 0:10:37.840 --> 0:10:40.800 I'll explain more, but first let's take a quick break. 0:10:50.280 --> 0:10:53.240 So doctor Hurst and his team figured that they might 0:10:53.320 --> 0:10:59.040 actually have some applications for this conductive paper beyond the 0:11:00.040 --> 0:11:05.440 lot of charges. Using a vandograph accelerator, and he thought 0:11:05.480 --> 0:11:09.400 that he could make this into a touch screen interface, 0:11:09.840 --> 0:11:14.480 so this would be a resistive touch screen. They actually 0:11:14.559 --> 0:11:17.640 have more layers than capacitive touch screens. That also means 0:11:17.640 --> 0:11:21.560 they block a little more light than capacitive touchscreens do, 0:11:21.720 --> 0:11:26.000 so resistive screens tend to be dimmer than capacitive ones. 0:11:26.559 --> 0:11:28.760 So let's go through those layers again, and again we're 0:11:28.800 --> 0:11:31.559 going to start from the display side up to the 0:11:31.640 --> 0:11:35.360 surface where you would make contact with the screen. So 0:11:35.440 --> 0:11:37.760 at the very base you've still got your display, just 0:11:37.800 --> 0:11:41.480 like with capacitive. On top of the display, you've got 0:11:41.480 --> 0:11:46.600 a glass substrate. Above that, you have a transparent conductive layer, 0:11:47.000 --> 0:11:48.719 so again similar to what you would have with the 0:11:48.760 --> 0:11:52.560 capacitive screen. But next you would have a layer of 0:11:52.600 --> 0:11:56.160 what are called separator dots. So these are our little 0:11:56.160 --> 0:11:58.199 supports that are non conductive. 0:11:59.400 --> 0:12:03.079 They are there to act as a separator. 0:12:03.360 --> 0:12:09.640 They keep the first transparent conductive layer separate from a 0:12:09.880 --> 0:12:15.080 second transparent conductive layer, so they're there to keep space 0:12:15.120 --> 0:12:20.040 between those two layers. So again above these separator dots 0:12:20.160 --> 0:12:23.559 is that second transparent conductive layer. And then on the 0:12:23.640 --> 0:12:28.200 very top you have a flexible transparent film on top. 0:12:28.559 --> 0:12:30.960 This is where you would make contact with the screen. 0:12:31.760 --> 0:12:36.000 So when you push down on the screen, whether it's 0:12:36.040 --> 0:12:39.400 with a conductive surface or not, what you're doing is 0:12:39.440 --> 0:12:45.679 you're deforming the top most transparent layer to push down 0:12:45.720 --> 0:12:49.400 and come into contact with the next transparent conductive layer. 0:12:49.840 --> 0:12:54.720 That creates a circuit. So as long as you're pushing 0:12:54.760 --> 0:12:58.000 down with enough force, you're creating the circuit and it 0:12:58.040 --> 0:13:04.240 will detect that. So typically you've got other circuits in 0:13:04.280 --> 0:13:07.959 the device that detect drops in voltage or changes in voltage, 0:13:08.200 --> 0:13:12.439 and that's how they can detect the precise location where 0:13:12.480 --> 0:13:16.080 the touch happened. So again doesn't matter if it's your finger, 0:13:16.559 --> 0:13:21.000 if you're wearing gloves, if you're using a stylus, it 0:13:21.040 --> 0:13:25.199 doesn't really matter. What matters is that that top transparent 0:13:25.520 --> 0:13:29.400 conductive layer comes into contact with the bottom transparent conductive 0:13:29.480 --> 0:13:33.600 layer and creates a circuit. So the capacitive screen actually 0:13:33.600 --> 0:13:38.160 came first, but the resistive screen was more popular. It 0:13:38.240 --> 0:13:41.360 got more popular, and it did so faster than capacitive. 0:13:41.440 --> 0:13:47.240 So why is that, Well, mostly it comes down to cost. Also, 0:13:47.480 --> 0:13:49.160 like the fact that you didn't have to have a 0:13:49.200 --> 0:13:52.680 conductive material to work with it meant that you could 0:13:52.679 --> 0:13:55.880 actually use it for lots of other stuff, including stuff 0:13:55.920 --> 0:13:58.040 where you might have to do something like wear gloves, 0:13:58.400 --> 0:14:02.040 but you could use a stylus like That's a useful 0:14:02.600 --> 0:14:04.439 part of that technology is the fact that you can 0:14:04.480 --> 0:14:07.280 still work with it even if you aren't able to, 0:14:07.920 --> 0:14:11.440 you know, use your fingers directly on the screen. But 0:14:11.480 --> 0:14:13.920 it was much cheaper, and that was really the big thing. 0:14:14.080 --> 0:14:17.720 So capacitive sort of took a back seat for a while, 0:14:17.840 --> 0:14:20.520 and it would require a lot more innovation in the 0:14:20.560 --> 0:14:25.160 space to make capacitive screens more attractive than resistive screens. However, 0:14:25.280 --> 0:14:28.400 these days, most consumer devices you're going to come into 0:14:28.400 --> 0:14:33.680 contact with use capacitive touch screens, largely because I mean, 0:14:33.720 --> 0:14:36.760 they're still more expensive than resistive touch screens, but they 0:14:36.800 --> 0:14:41.120 can display brighter images, so that's that's definitely a positive. 0:14:41.760 --> 0:14:42.520 They tend to. 0:14:42.480 --> 0:14:45.120 Be more durable as well as you can imagine if 0:14:45.160 --> 0:14:48.200 you've got a resistive touch screen, which is it works 0:14:48.320 --> 0:14:51.240 based upon you pushing the screen hard enough to make 0:14:51.280 --> 0:14:53.880 contact between two layers. I mean, you don't have to 0:14:53.880 --> 0:14:56.600 push super hard, but it does have to be enough 0:14:56.640 --> 0:15:02.320 pressure so that the some detects. There's a touch there well. 0:15:02.560 --> 0:15:08.600 As you might imagine, this eventually deforms the upper transparent 0:15:08.640 --> 0:15:11.840 conductive layer, and that you can eventually get to points 0:15:11.880 --> 0:15:15.280 where it's already close to or making contact with the 0:15:15.320 --> 0:15:18.280 lower layer. Just kind of like having a short circuit, right, 0:15:19.360 --> 0:15:24.200 and it makes it more difficult to have an accurate experience. 0:15:24.280 --> 0:15:28.520 Using resistive touch screens doesn't happen overnight, but over time 0:15:28.560 --> 0:15:32.560 it does happen. So that's one of the other benefits 0:15:32.560 --> 0:15:37.640 capacitive touch screens have over resistive. It's also easier to 0:15:37.760 --> 0:15:41.160 use capacitive touch screens for multi touch functions in general, 0:15:42.760 --> 0:15:45.120 not that you couldn't do it with resistive touch screens, 0:15:45.160 --> 0:15:47.680 but it's just it's easier when you're not focusing on 0:15:48.840 --> 0:15:52.720 using pressure to make that point of contact. You will 0:15:52.760 --> 0:15:55.800 still find resistive touch screens, however, in devices that are 0:15:55.800 --> 0:15:59.440 aimed at lower price points, So if you're looking at 0:15:59.480 --> 0:16:02.440 like a Budge tablet, there are a lot of industrial 0:16:02.560 --> 0:16:06.280 uses for resistive touch screens to this day. And keep 0:16:06.320 --> 0:16:09.720 in mind, as I said at the beginning of this episode, 0:16:09.840 --> 0:16:13.240 there are other types of touch screen technologies besides these two. 0:16:13.280 --> 0:16:17.120 There's some that use acoustics, there're some that use infra 0:16:17.160 --> 0:16:20.600 red lasers. Like I said, with the surface, there are 0:16:20.640 --> 0:16:23.680 the kinds that use you know, cameras that are mounted 0:16:23.720 --> 0:16:27.080 behind the screen itself. It's not like these two are 0:16:27.120 --> 0:16:29.920 the only two. There are lots of other technologies. It's 0:16:30.000 --> 0:16:32.040 just those two are the ones you're most likely to 0:16:32.040 --> 0:16:37.280 come into contact with, both figuratively and literally. So I 0:16:37.320 --> 0:16:41.880 hope that this was interesting and informative, a little text 0:16:41.920 --> 0:16:45.400 off tidbits episode, and I'm trying to do more of 0:16:45.440 --> 0:16:48.840 these because it's fun to do these short ones. It's 0:16:48.880 --> 0:16:51.640 just a challenge because you know, I'm a chatty kathy. 0:16:51.800 --> 0:16:53.720 This episode probably could have been eight minutes long and 0:16:53.720 --> 0:16:57.560 instead of going twice as long. So but hey, I 0:16:57.680 --> 0:17:01.040 like your company, hope you like mine, And if you 0:17:01.120 --> 0:17:03.400 have any suggestions for little things that you would like 0:17:03.480 --> 0:17:06.080 explained in the tech space, even. 0:17:05.880 --> 0:17:08.720 If it's something like, hey, can you give a quick rundown. 0:17:08.280 --> 0:17:11.440 On logic gates and what those do or something along 0:17:11.480 --> 0:17:14.119 those lines, let me know and I'll look into it. 0:17:14.640 --> 0:17:17.720 And I hope you are all well and I'll talk 0:17:17.720 --> 0:17:27.960 to you again really soon. Tech Stuff is an iHeartRadio production. 0:17:28.280 --> 0:17:33.280 For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple podcasts, 0:17:33.400 --> 0:17:35.399 or wherever you listen to your favorite shows.