1 00:00:00,080 --> 00:00:02,699 The year is 1954. 2 00:00:02,699 --> 00:00:08,320 After much deliberation, confusion, and fussing about, the FCC had, for the second time, settled 3 00:00:08,320 --> 00:00:12,599 on the way color TV would be transmitted in the United States, and Westinghouse would 4 00:00:12,599 --> 00:00:17,090 release the first commercially produced color television set using the new standard, the 5 00:00:17,090 --> 00:00:19,550 Westinghouse H840CK15. 6 00:00:19,550 --> 00:00:22,790 Ah, the H840CK15. 7 00:00:22,790 --> 00:00:24,150 Really rolls off the tongue. 8 00:00:24,150 --> 00:00:28,310 RCA would follow with the more famous CT-100 weeks later. 9 00:00:28,310 --> 00:00:32,020 The reason for the fussing about had to do with compatibility. 10 00:00:32,020 --> 00:00:36,600 Most experimental color televisions used complicated schemes to create a color image which would 11 00:00:36,600 --> 00:00:40,290 not be compatible with existing black and white televisions sets. 12 00:00:40,290 --> 00:00:45,090 It seemed like this was an inevitability, and the FCC did briefly approve simultaneous 13 00:00:45,090 --> 00:00:49,730 transmission of both color and black and white signals, creating a fragmented television 14 00:00:49,730 --> 00:00:50,860 landscape. 15 00:00:50,860 --> 00:00:56,010 But the National Television System Committee, NTSC, having backed the work of RCA, would 16 00:00:56,010 --> 00:00:59,290 save the day by introducing a new color system. 17 00:00:59,290 --> 00:01:04,750 Their compatible color managed to, in a sense, hide the color signal within the black-and-white 18 00:01:04,750 --> 00:01:05,750 transmission. 19 00:01:05,750 --> 00:01:09,261 The benefits of a single transmission for both color and black and white television 20 00:01:09,261 --> 00:01:14,270 sets were obvious, and though it took some convincing, the FCC would later decide that 21 00:01:14,270 --> 00:01:16,670 new NTSC color was the way to go. 22 00:01:16,670 --> 00:01:20,740 To understand this story, we need to look at how color images are made. 23 00:01:20,740 --> 00:01:25,430 Our eyes actually only see three colors of light--Red, green, and blue. 24 00:01:25,430 --> 00:01:29,620 Our brains interpret other colors by comparing the amount of each of the three colors we 25 00:01:29,620 --> 00:01:34,470 see, for example yellow light will stimulate both the red and green cells in your eyes 26 00:01:34,470 --> 00:01:39,730 in close to equal amounts as yellow lies between green and red on the color spectrum. 27 00:01:39,730 --> 00:01:44,000 We knew this for a long time before television was around, in fact this knowledge can be 28 00:01:44,000 --> 00:01:49,110 traced back to 1802 with Thomas Young’s pretty correct postulation. 29 00:01:49,110 --> 00:01:53,860 This was further refined in 1850 by Hermann von Helmholtz and thenceforth was known as 30 00:01:53,860 --> 00:01:56,360 the Young-Helmholtz theory. 31 00:01:56,360 --> 00:02:00,800 Experiments in color photography were done almost as soon as we figured out photography, 32 00:02:00,800 --> 00:02:05,170 and the three-color method, as suggested by Scottish physicist James Clerk Maxwell based 33 00:02:05,170 --> 00:02:07,970 on the Young-Helmholtz theory, worked perfectly. 34 00:02:07,970 --> 00:02:12,820 Plenty of very old color photographs exist, and this one is perhaps my favorite. 35 00:02:12,820 --> 00:02:17,020 The only clue that this photograph is from 1912 is the moustache. 36 00:02:17,020 --> 00:02:21,020 Anyway, with humans possessing the knowledge of how to recreate an image in color using 37 00:02:21,020 --> 00:02:25,650 an RGB system, it should be no surprise that we threw our hats into the ring for color 38 00:02:25,650 --> 00:02:27,920 television as soon as we figured out television. 39 00:02:27,920 --> 00:02:32,450 The first color television demonstration was done by none other than our friend John Logie 40 00:02:32,450 --> 00:02:35,300 Baird, who adapted his mechanical television system 41 00:02:35,300 --> 00:02:39,190 to produce color all the way back in 1928. 42 00:02:39,190 --> 00:02:42,920 But as we know, mechanical television was not meant for this world. 43 00:02:42,920 --> 00:02:45,920 CRT based electronic television was far superior. 44 00:02:45,920 --> 00:02:50,610 So, we got to work figuring on out how to adapt a CRT into a color display. 45 00:02:50,610 --> 00:02:55,860 The most obvious thing would be to simultaneously transmit three separate television images, 46 00:02:55,860 --> 00:02:58,900 with each representing one of the RGB channels. 47 00:02:58,900 --> 00:03:03,470 A special camera with a beam-splitting arrangement behind the lens could send the image to three 48 00:03:03,470 --> 00:03:08,010 separate iconoscope tubes, each with a colored filter in front of it. 49 00:03:08,010 --> 00:03:13,130 Later cameras would use dichroic glass to simultaneously split the beam and filter color. 50 00:03:13,130 --> 00:03:17,120 This would cause each tube to only detect light of that color. 51 00:03:17,120 --> 00:03:21,090 On the receiving end, three separate television picture tubes could receive each of these 52 00:03:21,090 --> 00:03:22,590 three signals. 53 00:03:22,590 --> 00:03:25,420 RCA experimented with just such a system. 54 00:03:25,420 --> 00:03:29,980 The three CRT displays were tinted either red, green, or blue, to match the colors detected 55 00:03:29,980 --> 00:03:31,780 by the tubes in the camera. 56 00:03:31,780 --> 00:03:34,470 The trick was combining the images together. 57 00:03:34,470 --> 00:03:39,459 An optical system similar to that of the camera could re-combine the output of the three CRTs, 58 00:03:39,459 --> 00:03:41,910 but this didn’t work too well. 59 00:03:41,910 --> 00:03:46,819 Though CRT projection systems would use this approach years later, at the time it wasn’t 60 00:03:46,819 --> 00:03:47,950 a great option. 61 00:03:47,950 --> 00:03:51,840 Besides the fact that each television set using this system would cost at least three 62 00:03:51,840 --> 00:03:56,740 times as much as an ordinary television, given the fact it essentially is three TVs, the 63 00:03:56,740 --> 00:04:01,379 resulting image had to be recombined onto a frosted screen, and with the comparatively 64 00:04:01,379 --> 00:04:04,640 dim tubes of the time, it just wasn’t great. 65 00:04:04,640 --> 00:04:08,709 The real trick would be to figure out how to use just one picture tube. 66 00:04:08,709 --> 00:04:11,300 Once again, John Logie Baird appeared. 67 00:04:11,300 --> 00:04:15,740 In 1940, he demonstrated a sequential color system using CRT technology. 68 00:04:15,740 --> 00:04:20,479 But, I’ve also found a source indicating this was in 1939. 69 00:04:20,479 --> 00:04:24,809 Also in 1940, CBS demonstrated their sequential color system. 70 00:04:24,809 --> 00:04:27,900 Regardless of who was first, both of these systems are similar. 71 00:04:27,900 --> 00:04:31,939 These work by placing a large disk in front of a black and white picture tube. 72 00:04:31,939 --> 00:04:36,539 This disc contained alternating sections tinted red, green, and blue. 73 00:04:36,539 --> 00:04:40,309 This disc was quite a bit larger than the tube, so that only one color was in front 74 00:04:40,309 --> 00:04:41,900 of the tube at one time. 75 00:04:41,900 --> 00:04:45,900 The disc would tint the apparent color of the picture tube, and by spinning the disc 76 00:04:45,900 --> 00:04:50,680 quickly in front of it, it would rapidly produce a red, then green, then blue image. 77 00:04:50,680 --> 00:04:55,180 If you do this fast enough, persistence of vision will kick in, and you won’t notice it. 78 00:04:55,180 --> 00:04:59,020 A similar disc was placed in front of the camera tube in the studio, so that it would 79 00:04:59,020 --> 00:05:01,680 only see red, then green, the blue light. 80 00:05:01,680 --> 00:05:06,879 So long as you can synchronize the camera and TV, you could transmit a full color image. 81 00:05:06,879 --> 00:05:09,939 But now is where we run into problems of compatibility. 82 00:05:09,939 --> 00:05:13,659 You could in theory just slap one of these discs in front of both a conventional camera 83 00:05:13,659 --> 00:05:18,819 and conventional TV, and it would work, but it would be painful to view. 84 00:05:18,819 --> 00:05:22,900 With a framerate of 30 frames per second, each color would only appear in front of the 85 00:05:22,900 --> 00:05:25,029 tube 10 times per second. 86 00:05:25,029 --> 00:05:26,050 This would be obvious. 87 00:05:26,050 --> 00:05:30,930 In fact, avert your eyes if you suffer from epilepsy, it would look like this. 88 00:05:30,930 --> 00:05:32,520 This isn’t great, now is it? 89 00:05:32,520 --> 00:05:37,520 Even if you spun the disc twice as fast and tinted each consecutive field and not frame, 90 00:05:37,520 --> 00:05:39,750 it would still be very visible. 91 00:05:39,750 --> 00:05:40,750 And now, 92 00:05:40,750 --> 00:05:44,979 I was pleasantly surprised to learn of Guillermo González Camarena, a Mexican inventor who 93 00:05:44,979 --> 00:05:49,879 applied for a patent detailing a system much like we’ve just discussed in 1940. 94 00:05:49,879 --> 00:05:52,849 Thanks to multiple commenters for letting me know about him. 95 00:05:52,849 --> 00:05:54,990 Information about him is very spotty. 96 00:05:54,990 --> 00:05:59,279 For example, there is a Wikipedia entry on him, but it’s pretty paltry and also somewhat 97 00:05:59,279 --> 00:06:00,839 contradicts itself. 98 00:06:00,839 --> 00:06:04,479 The actual patent is easily accessible, though, and it’s worth taking a look at. 99 00:06:04,479 --> 00:06:08,360 We’ll explore Camarena’s work in more detail in the next video, including his work 100 00:06:08,360 --> 00:06:12,530 on two-color TV, but first I need to address a small issue. 101 00:06:12,530 --> 00:06:16,689 His patent was to adapt an existing black-and-white set to color. 102 00:06:16,689 --> 00:06:21,160 This wouldn’t look too good, as we just discussed, as the color wouldn’t change fast enough. 103 00:06:21,240 --> 00:06:25,720 It would technically work, but its practical viewability would be questionable. 104 00:06:25,729 --> 00:06:30,529 He had the idea fundamentally correct, but the CBS system produced far and away better 105 00:06:30,529 --> 00:06:31,529 results. 106 00:06:31,529 --> 00:06:36,490 Also, CBS’s demonstration to the press of their field-sequential color-system happened 107 00:06:36,490 --> 00:06:40,020 just 9 days after Guillermo filed his patent. 108 00:06:40,020 --> 00:06:43,610 So here we are again, with multiple people who could be given credit as the inventor 109 00:06:43,610 --> 00:06:45,219 of color TV. 110 00:06:45,219 --> 00:06:47,409 So we’ll just say it was a group effort. 111 00:06:47,409 --> 00:06:50,330 CBS actually brought their system to commercial use. 112 00:06:50,330 --> 00:06:55,360 However, the CBS system radically altered the way television transmissions were done. 113 00:06:55,360 --> 00:06:59,199 To get around the high flicker caused by the color wheel, they elected to increase the 114 00:06:59,199 --> 00:07:05,419 field rate from 60 hz to 144 hz, but in order for each two-field frame to be completely 115 00:07:05,419 --> 00:07:10,020 colored, the wheel needed to cycle through the RGB pattern twice with each frame, reducing 116 00:07:10,020 --> 00:07:13,569 the effective frame rate to 24 frames per second. 117 00:07:13,569 --> 00:07:17,529 This was very effective at making the color wheel hard to notice since it changed colors 118 00:07:17,529 --> 00:07:23,539 144 times per second, but it came at the huge expense of wiping out any compatibility with 119 00:07:23,539 --> 00:07:25,499 existing black and white televisions. 120 00:07:25,499 --> 00:07:27,819 But, the color wheel was simple. 121 00:07:27,819 --> 00:07:31,780 Aside from the extra circuitry required to synchronize the wheel with the correct fields, 122 00:07:31,780 --> 00:07:35,710 it was really a run-of-the-mill black and white TV and camera, both modified with a 123 00:07:35,710 --> 00:07:40,370 much higher scan frequency, and with a spinning color wheel in front of each of them. 124 00:07:40,370 --> 00:07:44,849 It was easy to produce and worked reasonably well, and so the FCC decided they would allow 125 00:07:44,849 --> 00:07:47,569 broadcasting of the CBS color system. 126 00:07:47,569 --> 00:07:53,080 On June 25th, 1951, the first network color television broadcast occurred. 127 00:07:53,080 --> 00:07:59,069 But this whole time, RCA was trying to convince the FCC of their “compatible color” system. 128 00:07:59,069 --> 00:08:02,949 They understood that if would be really great if you could broadcast a color transmission 129 00:08:02,949 --> 00:08:06,520 that could still be viewed with the black and white televisions already in service. 130 00:08:06,520 --> 00:08:11,069 And to make that possible, they needed a whole new type of picture tube. 131 00:08:11,069 --> 00:08:12,999 Enter the shadow mask. 132 00:08:12,999 --> 00:08:16,939 One simple way to make a color picture tube would be to create a pattern of alternating 133 00:08:16,939 --> 00:08:20,319 red, green, and blue dots on the inside surface. 134 00:08:20,319 --> 00:08:24,259 From far enough away these dots would blend into each other and wouldn’t be noticeable. 135 00:08:24,259 --> 00:08:29,559 So, RCA used picture tubes which contained just an arrangement, with each dot being filled 136 00:08:29,559 --> 00:08:32,760 with either a red, green, or blue phosphor. 137 00:08:32,760 --> 00:08:36,840 This tube could be scanned at the same field and frame rate as an ordinary black and white 138 00:08:36,840 --> 00:08:39,630 tube, but could produce a full color image. 139 00:08:39,630 --> 00:08:42,640 But now you need a way to control which dots are lit up. 140 00:08:42,640 --> 00:08:45,470 If they all worked together, it would simply appear as black and white. 141 00:08:45,470 --> 00:08:48,910 You need a way to control where the electron beam lands. 142 00:08:48,910 --> 00:08:51,160 The shadow mask is just the solution. 143 00:08:51,160 --> 00:08:56,560 The 1938 invention of German man Werner Flechsig is a sheet of metal with a bunch of tiny holes 144 00:08:56,560 --> 00:08:57,820 punched through it. 145 00:08:57,820 --> 00:09:01,540 The shadow mask sits just behind the grid of phosphors. 146 00:09:01,540 --> 00:09:07,200 The holes work in conjunction with three separate electron guns, one for each color of phosphor, 147 00:09:07,200 --> 00:09:08,960 in the neck of the picture tube. 148 00:09:08,960 --> 00:09:13,310 These guns are arranged in a triangular pattern, and their beams converge right at the shadow 149 00:09:13,310 --> 00:09:14,370 mask. 150 00:09:14,370 --> 00:09:18,700 The mask prevents the beams from landing on the wrong color, as the beam can only pass 151 00:09:18,700 --> 00:09:23,560 through the mask at a certain angle, thus ensuring there’s no accidental cross-over. 152 00:09:23,560 --> 00:09:28,470 This is why placing a magnet near the face of a color CRT makes such far-out patterns 153 00:09:28,470 --> 00:09:29,590 appear. 154 00:09:29,590 --> 00:09:37,120 The magnet bends the beam after the shadow mask, and thus the electron beams land where they shouldn't. 155 00:09:38,430 --> 00:09:41,440 Now comes the time to explain the thumbnail of this video. 156 00:09:41,440 --> 00:09:45,700 It’s very important to understand that the individual groupings of red, green, and blue 157 00:09:45,700 --> 00:09:48,540 phosphors are NOT pixels. 158 00:09:48,540 --> 00:09:53,481 The TV set isn’t even trying to line the beam up with these triads, if you will, and 159 00:09:53,481 --> 00:09:56,390 it has no way to address them individually. 160 00:09:56,390 --> 00:10:01,180 In fact, the pattern of triads in this picture tube doesn’t even form a grid, as each adjacent 161 00:10:01,180 --> 00:10:04,290 column of triads is shifted up half way. 162 00:10:04,290 --> 00:10:09,330 But that makes sense when you keep in mind that the electron guns are arranged in a triangle--logically 163 00:10:09,330 --> 00:10:12,250 the targets they aim to hit would be, too. 164 00:10:12,250 --> 00:10:14,970 And before you bring up Trinitron, I’ll be addressing that in another video. 165 00:10:14,970 --> 00:10:16,510 Hold your commenting horses. 166 00:10:16,510 --> 00:10:20,560 To form an image, the face of the tube is scanned in horizontal lines just like a black 167 00:10:20,560 --> 00:10:21,990 and white television set. 168 00:10:21,990 --> 00:10:26,170 It’s these lines that make up the image, not the dots on the screen. 169 00:10:26,170 --> 00:10:32,020 This is the precise reason why I used a black and white TV in my video on how analog television works. 170 00:10:32,020 --> 00:10:35,620 The lines are obvious on a black and white set, but a color set makes them less so. 171 00:10:35,620 --> 00:10:39,830 It’s tempting to imagine these groupings as pixels, but in reality they are simply 172 00:10:39,830 --> 00:10:44,360 a regular pattern of dots which, when combined with the shadow mask, force each individual 173 00:10:44,360 --> 00:10:47,570 electron beam into its respective color. 174 00:10:47,570 --> 00:10:51,380 This is most easily demonstrated with white text on a black background, so let’s pull 175 00:10:51,380 --> 00:10:53,160 out the old PlayStation. 176 00:11:05,840 --> 00:11:10,030 The text here doesn’t fall nicely in line with the individual phosphor groupings. 177 00:11:10,030 --> 00:11:13,850 All around the edges of the text, the phosphor groupings are only partially lit. 178 00:11:13,850 --> 00:11:18,351 That’s because the scan line isn’t landing nicely within the center of the triads, and 179 00:11:18,351 --> 00:11:21,060 it just barely grazes the bottom of these triads. 180 00:11:21,060 --> 00:11:25,030 But it doesn’t matter, as the position of the shadow mask and phosphor triads is irrelevant 181 00:11:25,030 --> 00:11:28,170 to the scanning beam--the beam can land anywhere it wants. 182 00:11:28,170 --> 00:11:32,560 But the shadow mask will always prevent each individual color component of the beam from 183 00:11:32,560 --> 00:11:34,360 hitting the incorrect phosphor. 184 00:11:34,360 --> 00:11:39,000 The shadow mask worked really well, but it required very powerful electron beams. 185 00:11:39,000 --> 00:11:44,920 About 85 percent of the beam energy is lost just in the shadow mask, so only 15 percent 186 00:11:44,920 --> 00:11:46,940 gets through the tiny holes. 187 00:11:46,940 --> 00:11:51,230 Without really powerful electron guns, a dim image would result. 188 00:11:51,230 --> 00:11:55,850 Even with suitable electron guns, early color CRT displays were often less bright than their 189 00:11:55,850 --> 00:11:57,610 black and white counterparts. 190 00:11:57,610 --> 00:12:02,660 Nevertheless, it meant that the picture tube could on its own produce a full color image. 191 00:12:02,660 --> 00:12:06,810 The real challenge then was to find a way to transmit color television in a way that 192 00:12:06,810 --> 00:12:11,860 a color set could interpret but that would still work for existing black and white TVs. 193 00:12:11,860 --> 00:12:17,100 You could simultaneously transmit three separate monochrome images and assign one to the green 194 00:12:17,100 --> 00:12:21,130 electron gun, another to the red, and the final to the blue. 195 00:12:21,130 --> 00:12:24,500 But which one would you have the black and white television receive? 196 00:12:24,500 --> 00:12:28,990 Picking just one color would produce a very unnatural image on the black and white set. 197 00:12:28,990 --> 00:12:34,230 Also, this would triple the bandwidth needed, which wasn’t really gonna fly with the FCC. 198 00:12:34,230 --> 00:12:39,210 Stay tuned as in the next video, we’ll explore how RCA managed the seemingly impossible task 199 00:12:39,210 --> 00:12:45,880 of sending three times the data without needing more bandwidth--by hiding the color in plain sight. 200 00:12:46,000 --> 00:12:48,880 Thanks so much for watching, I really hope you enjoyed the video! 201 00:12:48,880 --> 00:12:52,160 If you’re new to this channel and like what you see, please consider subscribing. 202 00:12:52,160 --> 00:12:55,920 I’d also like to thank all of my Patreon supporters, with a special thanks to these 203 00:12:55,920 --> 00:12:57,930 people who get their name in lights! 204 00:12:57,930 --> 00:13:02,660 Your can support me and this channel by visiting the link on your screen or in the description, 205 00:13:02,660 --> 00:13:04,700 and I thank you for your consideration. 206 00:13:04,700 --> 00:13:06,180 I’ll see you next time!