WEBVTT Kind: captions Language: en 00:00:00.089 --> 00:00:06.310 Philo Farnsworth is nearly universally given credit as the inventor of electronic television. 00:00:06.310 --> 00:00:10.930 His first transmission of an image via his television system occurred in 1927, and it 00:00:10.930 --> 00:00:15.200 was an incredibly big deal. But his invention had less to do with the television in your 00:00:15.200 --> 00:00:20.710 house, and more to do with the camera in the studio. Today, we’ll be exploring how Philo 00:00:20.710 --> 00:00:25.390 Farnsworth brought television out of the realm of mechanical contraptions and into the landscape 00:00:25.390 --> 00:00:26.840 of pure electronics. 00:00:26.840 --> 00:00:31.440 You see, the cathode ray tube, the device which effectively is the screen of an old-style 00:00:31.440 --> 00:00:36.760 television, was invented in the 19th century, decades before Farnsworth made his contribution. 00:00:36.760 --> 00:00:41.481 The trouble was no one had yet figured out how to turn a CRT into a television. When 00:00:41.481 --> 00:00:46.310 Baird invented his mechanical television, the holes in the spinning disc served both 00:00:46.310 --> 00:00:50.739 as a scanning device, creating a signal from an image focused onto it as the holes traveled 00:00:50.739 --> 00:00:55.590 past, AND as a display device, reconstructing the image as a light source duplicated the 00:00:55.590 --> 00:00:59.870 intensity and location of each part of the scanning device, with the holes moving the 00:00:59.870 --> 00:01:04.799 light’s apparent location to recreate the image line by line. With the CRT being pretty 00:01:04.799 --> 00:01:08.659 thoroughly researched, it wouldn’t take too much imagination to create an image with 00:01:08.659 --> 00:01:12.979 a moving electron beam. But what was unknown was how to use a similar device to create 00:01:12.979 --> 00:01:15.929 a signal to actually run a CRT display. 00:01:15.929 --> 00:01:19.689 As I worked out in my last video, to use a mechanical scanning method like in the Baird 00:01:19.689 --> 00:01:24.189 system to achieve equivalent image quality of a US CRT television, the scanning disc 00:01:24.189 --> 00:01:28.421 would have to be impractically large, and it would have to spin impossibly fast. Even 00:01:28.421 --> 00:01:33.950 if the lens focused on just a 3 centimeter wide target, a 525 line scanning disc would 00:01:33.950 --> 00:01:38.569 be 5 meters tall, and the edges would still be breaking the sound barrier for 30 complete 00:01:38.569 --> 00:01:40.039 frames per second. 00:01:40.039 --> 00:01:43.579 There were other ways to use a mechanical scanning device, though. One of these was 00:01:43.579 --> 00:01:48.279 the so-called “Flying Spot” system. With these systems, a mechanical disc in front 00:01:48.279 --> 00:01:53.579 of an extremely bright arc lamp would project a scanning pattern on a performer’s face, 00:01:53.579 --> 00:01:57.450 and a simple light sensor pointed at the performer would measure the light reflected off of him 00:01:57.450 --> 00:02:02.080 or her for generating the signal, with only one spot hitting the performer at one time. 00:02:02.080 --> 00:02:04.929 The projection meant the mechanical disc could produce a 00:02:04.929 --> 00:02:09.399 much larger image than its physical size. The trouble with this approach, however, was 00:02:09.399 --> 00:02:13.099 that the performer would have to be in absolute darkness, and you still had to work around 00:02:13.099 --> 00:02:17.489 the poor resolution of mechanical systems on the receiving end. Plus, I imagine the 00:02:17.489 --> 00:02:21.920 strobing effect as the light shone across your eyes was fairly unpleasant for television 00:02:21.920 --> 00:02:23.569 talent of the day. 00:02:23.569 --> 00:02:27.849 Before Baird had even demonstrated his mechanical television, Farnsworth theorized a way to 00:02:27.849 --> 00:02:33.590 electronically convert an image into a transmittable electrical signal in 1921. This is part of 00:02:33.590 --> 00:02:38.189 why he is often regarded as television’s inventor. He was what you might call a prodigy, 00:02:38.189 --> 00:02:43.450 as in 1921 he was only 15. He grew up on a Utah farm, and the story goes that he came 00:02:43.450 --> 00:02:47.970 up with his idea after observing the lines drawn in the fields from a plow, realizing 00:02:47.970 --> 00:02:52.030 that by altering a line as it’s drawn over a distance, you could make an image from a 00:02:52.030 --> 00:02:57.530 field of lines. Perhaps this is why to this day, each half of an interlaced frame of video 00:02:57.530 --> 00:02:58.910 is called a field. 00:02:58.910 --> 00:03:04.370 Farnsworth submitted a patent application in January of 1927. However, Farnsworth wasn’t 00:03:04.370 --> 00:03:09.189 the only person trying to build an image dissector. In fact, the invention of television is very 00:03:09.189 --> 00:03:14.730 complicated and to say that one person invented it is rather simplistic. For example, before 00:03:14.730 --> 00:03:18.890 Farnsworth had his image dissector worked out, German professor Max Dieckmann and his 00:03:18.890 --> 00:03:25.319 student Rudolf Hell applied for a patent for…. This, in 1925. In fact, Dieckmann was among 00:03:25.319 --> 00:03:30.550 the first to demonstrate the display capability of the cathode ray tube back in 1906. And 00:03:30.550 --> 00:03:35.269 in the following year, a Russian scientist named Boris Rosing used a CRT with experimental 00:03:35.269 --> 00:03:40.340 “video” signals to create geometric shapes. See, there was a lot of experimentation going 00:03:40.340 --> 00:03:44.770 on all over the world. The wikipedia entry on the history of television, which is linked 00:03:44.770 --> 00:03:48.040 in the description, goes over this in much greater detail. 00:03:48.040 --> 00:03:52.240 Hell and Dieckmann’s patent was granted to them in October of 1927, but they were 00:03:52.240 --> 00:03:56.760 never able to produce a working model. Meanwhile, Farnsworth transmitted the first image with 00:03:56.760 --> 00:04:02.880 his image dissector at his laboratory in San Francisco on September the 7th, 1927. Farnsworth’s 00:04:02.880 --> 00:04:07.720 invention was very crude at this point, as it only really transmitted a line, and not 00:04:07.720 --> 00:04:12.160 a whole screen of an image. However, it was a revolutionary proof of concept. On September 00:04:12.160 --> 00:04:17.320 3rd, 1928, Farnsworth called a press conference, where he declared “Good news, everyone! 00:04:17.560 --> 00:04:23.360 I’ve invented television”. His demonstration of actually functional electronic television 00:04:23.560 --> 00:04:27.200 is generally accepted as the first, and it is for this reason that he’s often given 00:04:27.200 --> 00:04:29.300 credit as the inventor of television. 00:04:29.300 --> 00:04:33.669 Farnsworth’s image dissector was a vacuum tube much like a CRT, but instead of emitting 00:04:33.669 --> 00:04:38.430 light, the image dissector was meant to detect it. Inside the tube was a coating of caesium 00:04:38.430 --> 00:04:43.400 oxide, a photosensitive material. Caesium oxide has an interesting characteristic where 00:04:43.400 --> 00:04:48.700 when photons hit it, it emits electrons. This meant that an image focused with a lens onto 00:04:48.700 --> 00:04:53.099 the face of an image dissector would create a pattern of electron emissions in the shape 00:04:53.099 --> 00:04:58.389 and intensity of the image itself. Then, this electron image would be scanned. 00:04:58.389 --> 00:05:02.020 An electron beam very much like that which would be used to draw an image on the face 00:05:02.020 --> 00:05:07.550 of a CRT television receiver, would methodically scan the face of the image dissector. Now, 00:05:07.550 --> 00:05:12.440 as we all know, opposite attract, and likes repel--electrons really don’t like to hang 00:05:12.440 --> 00:05:17.270 out together. What happens when the electron beam encounters an area of the image dissector 00:05:17.270 --> 00:05:21.600 where bright light is hitting the surface? Well, the caesium oxide coating is itself 00:05:21.600 --> 00:05:25.840 producing electrons, so the electron beam would bounce back at areas where light was 00:05:25.840 --> 00:05:26.840 present. 00:05:26.840 --> 00:05:30.879 Ordinarily, most of the beam would just be absorbed by the oxide coating or even the 00:05:30.879 --> 00:05:35.110 tube’s glass. But any electrons sent by the gun that ran into a spot already filled 00:05:35.110 --> 00:05:40.010 with electrons emitted from the caesium oxide would be reflected back into the tube. The 00:05:40.010 --> 00:05:44.930 image dissector contained a detector of sorts that would collect these reflected electrons. 00:05:44.930 --> 00:05:48.860 By amplifying the output of the detector, a signal could be produced which corresponded 00:05:48.860 --> 00:05:52.780 to the exact image brightness of wherever the beam happened to be pointing on the surface 00:05:52.780 --> 00:05:57.509 of the image dissector. Deflect the beam in a raster pattern using electromagnetic fields 00:05:57.509 --> 00:06:01.449 from a deflection yoke, and you can scan the whole face of the dissector and generate a 00:06:01.449 --> 00:06:03.290 signal from the entire image. 00:06:03.290 --> 00:06:07.800 Here’s a more practical demonstration of what’s going on. This poster board represents 00:06:07.800 --> 00:06:11.520 the target of the scanning electron beam. The image we’re looking to capture is a 00:06:11.520 --> 00:06:17.069 simple white circle. A lens is focusing that circle onto the face of the image dissector. 00:06:17.069 --> 00:06:21.250 The circle of light, which moves us all, by the way, will cause the caesium oxide coating 00:06:21.250 --> 00:06:25.949 to emit electrons inside the tube wherever the light touches. We’ll represent electrons 00:06:25.949 --> 00:06:30.289 in red. Therefore, the circle will be filled with red electrons. It should be noted here 00:06:30.289 --> 00:06:34.380 that the resemblance to the Japanese flag was entirely accidental. It took me filling 00:06:34.380 --> 00:06:38.050 in over 90% of this to realize, Oh, that’s the flag of Japan. 00:06:38.050 --> 00:06:42.290 Anyway, the electron gun sits behind the caesium oxide (Pop sound) and it emits a string of 00:06:42.290 --> 00:06:46.040 yarn, I mean an electron beam (NES Zapper sound effect). Deflector magnets bend the 00:06:46.040 --> 00:06:50.980 electron beam, and will start scanning the image. For the first few lines, nothing extraordinary 00:06:50.980 --> 00:06:55.270 occurs as the electrons are just absorbed by the target. But, once the beam reaches 00:06:55.270 --> 00:06:59.860 the circle, it gets deflected back because electrons are already there. In other words, 00:06:59.860 --> 00:07:03.440 where the light touches, well the electrons must never go there. 00:07:03.440 --> 00:07:07.620 These deflected electrons get picked up by a collector electrode inside the tube, and 00:07:07.620 --> 00:07:12.319 by monitoring the output from this electrode, you get a signal which varies in intensity 00:07:12.319 --> 00:07:17.409 in proportion to the brightness of the spot the beam is currently scanning. So, reverse 00:07:17.409 --> 00:07:21.120 the process. Here’s a television receiver. It’s electron beam is following along the 00:07:21.120 --> 00:07:25.780 same path as the one in the image dissector, so if the scanning beam is aimed at one spot, 00:07:25.780 --> 00:07:30.139 the electron beam in the television set will be pointed at the same spot. Whenever the 00:07:30.139 --> 00:07:34.340 dissector detects light from the circle, the signal it produces will cause the television 00:07:34.340 --> 00:07:38.930 receiver to spit electrons out from its own electron gun. This will make the phosphors 00:07:38.930 --> 00:07:43.690 inside the tube glow in the same places that the dissector detected light, and at the same 00:07:43.690 --> 00:07:48.020 relative intensity. After the scanning is complete, the television will have drawn that 00:07:48.020 --> 00:07:52.310 circle. Do that really really fast and over and over again, and you’ve got yourself 00:07:52.310 --> 00:07:54.139 some mighty fine television. 00:07:54.139 --> 00:07:57.629 If you’re confused, and I wouldn’t blame you if you are, it might be helpful to check 00:07:57.629 --> 00:08:02.879 out my previous video on how analog television works. That video discusses the raster pattern, 00:08:02.879 --> 00:08:07.229 how the television synchronizes the image coherently via triggers built into the signal, 00:08:07.229 --> 00:08:11.400 and more in greater detail. Hopefully you’ll be able to see that the television camera 00:08:11.400 --> 00:08:15.700 tube is essentially the same thing as the cathode ray tube in a television set, but 00:08:15.700 --> 00:08:20.539 with the electron beam used as a way to detect the presence of light, rather than to reproduce 00:08:20.539 --> 00:08:24.930 it. You can find a link to the video down below, or hang around until the endscreen. 00:08:24.930 --> 00:08:29.979 Farnsworth’s image dissector was a big deal, but it kinda sucked. Because the beam has 00:08:29.979 --> 00:08:34.020 to move across the face of the dissector so quickly in order to produce an image, it has 00:08:34.020 --> 00:08:38.961 only the tiniest fraction of a second to actually encounter an electron on the surface and be 00:08:38.961 --> 00:08:43.890 deflected back. The caesium oxide coating wasn’t super great at producing electrons 00:08:43.890 --> 00:08:48.720 from light, so television cameras that used Farnsworth’s image dissector needed an insane 00:08:48.720 --> 00:08:54.350 amount of light in order to work. This meant studio lighting was absurdly bright--and hot--, 00:08:54.350 --> 00:08:57.230 and it generally presented unfortunate limitations. 00:08:57.230 --> 00:09:01.751 A much more practical device for producing television signals was the iconoscope. Here 00:09:01.751 --> 00:09:06.500 comes another person into the fold. Vladimir Zworykin filed patents for a television system 00:09:06.500 --> 00:09:11.710 in 1923 and 1925. If you’ve been paying attention, you’ll have noticed that these 00:09:11.710 --> 00:09:17.020 years predate Farnsworth’s patent application. I told you this was complicated. 00:09:17.020 --> 00:09:22.350 In 1923, Zworykin presented his idea to H P Davis, the general manager of Westinghouse, 00:09:22.350 --> 00:09:28.840 where he worked, and in 1925 he demonstrated the first prototype. However, it barely worked, 00:09:28.840 --> 00:09:32.840 and Davis wasn’t impressed. So unphased was Davis that he told Zworykin to work on 00:09:32.840 --> 00:09:36.900 something useful. Wwll. Zworykin would later work for RCA. 00:09:36.900 --> 00:09:40.540 The iconoscope functioned essentially the same as the image dissector, but there was 00:09:40.540 --> 00:09:43.910 one key difference. And Zworykin wasn’t the one who discovered the principle that 00:09:43.910 --> 00:09:49.550 would solve the problem. That was Hungarian engineer Kálmán Tihanyi. Too many people 00:09:49.550 --> 00:09:50.550 here. 00:09:50.550 --> 00:09:54.780 Anyway, the big deal with the iconoscope was that it didn’t rely solely on electrons 00:09:54.780 --> 00:09:59.350 emitted from the Caesium Oxide. Rather, it used a sheet of mica which had tiny silver 00:09:59.350 --> 00:10:03.760 particles coated with our friend Caesium Oxide on one side, and a thin film of plain old 00:10:03.760 --> 00:10:08.670 silver on the other. The separation of these two sheets provided by the mica essentially 00:10:08.670 --> 00:10:12.940 turned the thing into a giant capacitor, capable of storing electrons. 00:10:12.940 --> 00:10:17.160 When operating, the iconoscope would first send a steady sweep of electrons across the 00:10:17.160 --> 00:10:22.170 whole target. This would provide a uniform charge throughout the mica sheet. Light reflected 00:10:22.170 --> 00:10:26.410 from subjects in the studio and subsequently focused through a lens onto the target would 00:10:26.410 --> 00:10:30.430 cause the caesium oxide to emit electrons again in the spots hit with light, creating 00:10:30.430 --> 00:10:34.870 an electron copy of the image, and this would cause the charge stored between the layers 00:10:34.870 --> 00:10:40.220 to decay more rapidly than it would if no light were hitting it. The next time the target 00:10:40.220 --> 00:10:44.200 is scanned, areas that weren’t hit with light will still have electrons in them, which 00:10:44.200 --> 00:10:49.140 will resist the beam’s efforts to try and add more. This extra beam energy is reflected 00:10:49.140 --> 00:10:54.000 back and picked up by the detector ring. Areas that were hit with light would quickly lose 00:10:54.000 --> 00:10:59.510 their electrons, and the beam’s energy would instead be used to replenish these lost electrons. 00:10:59.510 --> 00:11:04.080 The iconoscope produced an inverted signal, as dark areas reflected the beam strongly, 00:11:04.080 --> 00:11:09.070 and bright areas didn’t reflect it much at all, but it was much, much, MUCH more sensitive 00:11:09.070 --> 00:11:13.160 than Farnsworth’s image dissector because it could store electrons in the mica sheet, 00:11:13.160 --> 00:11:17.100 and thus greatly increase the likelihood that the electron beam would actually be deflected 00:11:17.100 --> 00:11:18.790 back to the detector. 00:11:18.790 --> 00:11:22.671 One tricky bit about the iconoscope was that the light it was detecting and the electron 00:11:22.671 --> 00:11:28.220 beam had to hit the mica sheet from the same side. This is why the tube is such a weird 00:11:28.220 --> 00:11:31.830 shape. The electron gun can’t be in the line of sight of the target, so it’s tucked 00:11:31.830 --> 00:11:36.480 below the target screen at an angle. In a working camera, it’s actually in the front, 00:11:36.480 --> 00:11:40.590 resting below the lens. Electronics in the camera would adjust its scanning sweeps as 00:11:40.590 --> 00:11:44.770 it went to compensate for the keystone shape it would naturally produce if the beam was 00:11:44.770 --> 00:11:48.000 projected as a simple square at an upwards angle. 00:11:48.000 --> 00:11:53.530 A side effect of the way the iconoscope works is an image that can never truly be black. 00:11:53.530 --> 00:11:57.230 Electrons will decay from the mica screen without any light hitting it at all--light 00:11:57.230 --> 00:12:01.881 simply accelerates this decay. The detector ring would pick these rogue electrons up, 00:12:01.881 --> 00:12:06.340 and it would transmit as an entirely grey screen. There needed to be bright areas of 00:12:06.340 --> 00:12:10.280 the picture to pull down the average emission of the mica screen and make the other areas 00:12:10.280 --> 00:12:15.170 appear black--in other words, high contrast scenery was required. Lighting conditions 00:12:15.170 --> 00:12:19.160 would have to be accounted for to keep the averaging effect of the iconoscope from producing 00:12:19.160 --> 00:12:20.920 odd images. 00:12:20.920 --> 00:12:24.990 Because this episode is a circus of who-did-what, let’s drop one more name. The iconoscope 00:12:24.990 --> 00:12:30.240 design was immensely improved by accident in 1931 when Sanford Essig left one of the 00:12:30.240 --> 00:12:35.390 mica plates in the oven too long. This broke up the silver layer into tiny globules, which 00:12:35.400 --> 00:12:39.840 was responsible for increasing the resolution the iconoscope could detect immensely, 00:12:39.920 --> 00:12:44.400 Therefore, a sharper image was produced. So, don’t forget about him. 00:12:44.420 --> 00:12:49.320 Although the iconoscope was a great improvement over Farnsworth’s image dissector, it still 00:12:49.320 --> 00:12:53.650 wasn’t that great. The images were noisy, of poor resolution, and it still required 00:12:53.650 --> 00:12:59.050 a lot of light, though far less than the original disector did. RCA would develop the Image 00:12:59.050 --> 00:13:03.660 Orthicon tube in the 1940’s, and this much more sensitive device would be used into the 00:13:03.660 --> 00:13:09.120 1960s. The Image Orthicon tube combined principles from the iconoscope, image dissector, and 00:13:09.120 --> 00:13:11.130 the original Orthicon tube. 00:13:11.130 --> 00:13:16.210 The Orthicon tube (along with the Eurpoean CPS Emitron tube) contained deflector plates 00:13:16.210 --> 00:13:20.190 that when calibrated correctly would reduce the velocity of scanning electrons coming 00:13:20.190 --> 00:13:25.090 from the electron gun to near zero as they approached the target. This was immensely 00:13:25.090 --> 00:13:28.960 helpful, because without these deflectors, electrons could still bounce back into the 00:13:28.960 --> 00:13:34.060 detector ring without photoelectrons being present. This created for a noisy picture. 00:13:34.060 --> 00:13:38.080 Slowing the electrons down before they hit the target meant almost no rogue electrons 00:13:38.080 --> 00:13:42.320 would have enough gusto to make it back to the detector. Only those scanning electrons 00:13:42.320 --> 00:13:46.560 that actually encountered another electron at the target would make their way back, as 00:13:46.560 --> 00:13:50.390 the extra repelling force imparted by its photo-electric neighbor would help to push 00:13:50.390 --> 00:13:56.110 it backwards. This greatly reduced the grainy image noise associated with ordinary tubes. 00:13:56.110 --> 00:14:00.370 In addition to the electron slow-downy thing, the Image Orthicon tube used a neat physics 00:14:00.370 --> 00:14:04.920 trick to amplify the effect of the photoelectrons and make the whole thing more sensitive. In 00:14:04.920 --> 00:14:10.070 an image orthicon tube, the surface the light falls on to make the image, called the photocathode, 00:14:10.070 --> 00:14:14.720 and the surface the electron beam scans to make a signal, called the target, are separated 00:14:14.720 --> 00:14:19.350 by a fairly great distance. The photocathode is negatively charged, meaning electrons near 00:14:19.350 --> 00:14:23.740 it will want to fly away from it, and in front of the scanning target is a wire mesh with 00:14:23.740 --> 00:14:28.970 a slight positive charge used to attract the photoelectrons. This causes the photoelectrons 00:14:28.970 --> 00:14:33.870 emitted from the photocathode to be accelerated towards the scanning target. The separation 00:14:33.870 --> 00:14:38.370 of photocathode and target causes a dramatic increase in speed of the photoelectrons, which 00:14:38.370 --> 00:14:42.990 results in a multiplication of the electrons generated from the image. This happens because 00:14:42.990 --> 00:14:48.360 when an individual electron slams into the target at high speed, it causes a splash, 00:14:48.360 --> 00:14:53.580 forcing many electrons out of the target. This is called secondary emission, and a wire 00:14:53.580 --> 00:14:58.631 mesh behind the target with a slight positive potential traps these extra electrons. This 00:14:58.631 --> 00:15:01.690 phenomenon is used to greatly increase the tube’s sensitivity. 00:15:01.690 --> 00:15:05.830 You see, the extra electrons produced when the first photoelectron hit the target came 00:15:05.830 --> 00:15:10.890 from within the target itself. Essentially, the high-speed of the photoelectron knocks 00:15:10.890 --> 00:15:15.900 out a whole bunch of electrons when it hits the target. This causes a net loss of electrons 00:15:15.900 --> 00:15:21.200 in the area of impact, giving that area of the scanning target a slight positive charge. 00:15:21.200 --> 00:15:25.010 When the scanning beam from the electron gun runs over this area, the electrons it emits 00:15:25.010 --> 00:15:29.470 are first used to refill those lost from the secondary emission event. The result is that 00:15:29.470 --> 00:15:33.770 bright areas of the picture use the beam’s energy to recharge the target, and no electrons 00:15:33.770 --> 00:15:38.261 are reflected back and detected. Dark areas of the image don’t displace electrons in 00:15:38.261 --> 00:15:42.600 the target, so the beam is reflected back as electrons are already present, and a strong 00:15:42.600 --> 00:15:46.620 signal is produced via the dynodes and electron multiplier at the base of the tube. 00:15:46.620 --> 00:15:50.090 The image orthicon tube was a big deal for many reasons, not the least of which was that 00:15:50.090 --> 00:15:54.350 cameras could be much smaller and less awkward as the scanning portion of the tube was no 00:15:54.350 --> 00:15:59.130 longer in front of the imaging target. But it was also sensitive enough to capture scenes 00:15:59.130 --> 00:16:03.920 lit by candlelight, and its logarithmic light sensitivity matches that of the human eye, 00:16:03.920 --> 00:16:08.430 which made images produced from these tubes appear more natural. A fun little fact immortalized 00:16:08.430 --> 00:16:12.880 by Wikipedia regarding the image orthicon tube is that it’s directly responsible for 00:16:12.880 --> 00:16:18.410 the name of the award given by the Academy of Television Arts and Sciences. Image Orthicon 00:16:18.410 --> 00:16:22.730 tubes were often referred to informally as “Immys”. The presidents of the Academy 00:16:22.730 --> 00:16:27.770 at the time, Harry Lubcke, wanted to name the award after the Immy. But since the statuette 00:16:27.770 --> 00:16:30.850 is female, the more feminine “Emmy” was chosen. 00:16:30.850 --> 00:16:35.200 The inverted signals of the image orthicon and iconoscope--meaning bright areas produce 00:16:35.200 --> 00:16:39.450 little to no signal and dark areas produce a strong signal--wasn’t a problem as this 00:16:39.450 --> 00:16:43.900 is how television broadcasts were transmitted, anyway. It was up to your TV set to flip those 00:16:43.900 --> 00:16:44.900 values around. 00:16:44.900 --> 00:16:50.670 Phew. That was complicated. And I didn’t even mention Kenjiro Takayanagi’s 1926 demonstration 00:16:50.670 --> 00:16:55.670 in Japan of a CRT-based television system. Sadly he doesn’t get much credit because 00:16:55.670 --> 00:17:02.840 his camera was still mechanical using a Nipkow disc. There I said it. Nip-koff. OR, should 00:17:02.840 --> 00:17:07.179 it be nip-ko as some have suggested? I don’t know, maybe you should argue about it in the 00:17:07.179 --> 00:17:08.179 comments. 00:17:08.179 --> 00:17:11.639 There are so many dots to connect here that I’m not going to claim I got it all correct. 00:17:11.639 --> 00:17:15.399 For one thing, It’s hard to pin down how developments in Europe affected those in the 00:17:15.399 --> 00:17:20.370 US and vice versa, particularly due to the patent dispute between Farnsworth and Zworykin 00:17:20.370 --> 00:17:25.160 which made new developments dance around their respective technological claims. This is a 00:17:25.160 --> 00:17:29.741 large part of why I didn’t go into much detail on European tubes and systems. And 00:17:29.741 --> 00:17:34.169 all the names given to all the tubes is very confusing for creating a research timeline 00:17:34.169 --> 00:17:39.039 in me head. I’m welcome to all comments that may set records straight, so leave ‘em 00:17:39.039 --> 00:17:43.360 below. This video is long enough, so I’ll be ending it here. Stay tuned, as in the next 00:17:43.360 --> 00:17:47.740 video, we’ll be looking at the next big thing in TV--Color. 00:17:47.740 --> 00:17:51.289 Thanks for watching, I hope you enjoyed the video. I am delighted at the growth this channel 00:17:51.289 --> 00:17:54.389 is seeing and I’m glad you’re a part of it. If you’re new to this channel, why not 00:17:54.389 --> 00:17:57.910 hit that subscribe button? I’m doing my best to keep videos like this headed your 00:17:57.910 --> 00:18:00.120 way, and I’ll see you next time! 00:18:00.120 --> 00:18:04.080 And a special thanks to supporters on Patreon. You can support this channel through a totally 00:18:04.080 --> 00:18:07.850 voluntary contribution by visiting my page through the link in the description or the 00:18:07.850 --> 00:18:12.259 logo on our screen. With your support, you’re helping my to make my passion of sharing technological 00:18:12.259 --> 00:18:18.400 stories with you into a life-sustaining job, and for that I am ever so grateful. Thank you! 00:18:21.920 --> 00:18:22.480 (Oh no!) 00:18:25.520 --> 00:18:26.020 (Well...) 00:18:27.600 --> 00:18:29.440 (Might as well change the yarn again)