1 00:00:00,080 --> 00:00:01,820 Today’s video is about printers. 2 00:00:01,820 --> 00:00:06,080 I know, you’re probably filled with excitement at the mere mention of printers, but please 3 00:00:06,080 --> 00:00:07,560 remain calm. 4 00:00:07,560 --> 00:00:11,350 If you were to go shopping for a printer, you’ll almost certainly find yourself choosing 5 00:00:11,350 --> 00:00:14,549 between an inkjet printer and a laser printer. 6 00:00:14,549 --> 00:00:17,960 Or perhaps a 3D printer, but we’re not talking about those today. 7 00:00:17,960 --> 00:00:21,630 Now, I won’t get into the many reasons that I don’t really like inkjet printers for 8 00:00:21,630 --> 00:00:25,369 anything but photo printing because that’s not really the point of this video. 9 00:00:25,369 --> 00:00:28,783 Instead, we’re going to talk about a subset of the laser printer 10 00:00:28,783 --> 00:00:31,370 that seems to fly under the radar. 11 00:00:31,370 --> 00:00:32,900 The LED printer. 12 00:00:32,900 --> 00:00:35,500 Now, if you’ve never heard of this before I wouldn’t blame you. 13 00:00:35,500 --> 00:00:39,160 Fundamentally LED printers are the same as a laser printer. 14 00:00:39,160 --> 00:00:41,910 They still use powdered toner rather than liquid ink. 15 00:00:41,910 --> 00:00:46,530 They use photosensitive drums to transfer toner to paper (along with corona wires and/or 16 00:00:46,530 --> 00:00:49,370 other charge inducing or destroying doodads). 17 00:00:49,370 --> 00:00:54,220 And a fuser melts this toner onto the paper, so a tall stack of freshly printed printouts 18 00:00:54,220 --> 00:00:57,340 is nice and warm, just asking you to give it a hug. 19 00:00:57,340 --> 00:01:01,110 But where they differ is in how the image is drawn on the drum. 20 00:01:01,110 --> 00:01:04,910 And to understand why that’s important, let’s have a quick lesson into how laser 21 00:01:04,910 --> 00:01:07,000 printing works and how it came about. 22 00:01:07,000 --> 00:01:10,840 Laser printers are essentially an offshoot of the photocopier. 23 00:01:10,840 --> 00:01:15,340 Using a process called xerography, which comes from the Greek for dry writing (and now you 24 00:01:15,340 --> 00:01:21,000 know where Xerox got its name), analog photocopiers use a cylindrical drum coated in a photoconductive 25 00:01:21,000 --> 00:01:22,310 material. 26 00:01:22,310 --> 00:01:25,970 This material becomes conductive when exposed to light. 27 00:01:25,970 --> 00:01:30,240 To duplicate the image, the drum is first charged by a corona wire, which produces a 28 00:01:30,240 --> 00:01:33,390 high voltage and gives the drum a static charge. 29 00:01:33,390 --> 00:01:37,570 The now negatively charged drum is rolled underneath a piece of paper to be copied, 30 00:01:37,570 --> 00:01:42,250 where a lens focuses the image of the paper onto the drum, and a bright light source provides 31 00:01:42,250 --> 00:01:43,820 illumination. 32 00:01:43,820 --> 00:01:48,260 Because the photoconductive material will conduct electricity when exposed to light, 33 00:01:48,260 --> 00:01:53,340 any bright areas become discharged, as a path to ground can now be completed. 34 00:01:53,340 --> 00:01:56,320 Dark areas, where printing or handwriting exist on the original, 35 00:01:56,320 --> 00:01:58,490 will remain negatively charged. 36 00:01:58,490 --> 00:02:03,510 This drum is then rolled against a supply of powdered toner, which is positively charged. 37 00:02:03,510 --> 00:02:07,780 This toner will thus want to stick to any areas of the drum that remained negatively 38 00:02:07,780 --> 00:02:10,320 charged from the original exposure. 39 00:02:10,320 --> 00:02:14,640 Now the drum has a coating of powdered toner in the same pattern as the writing or image 40 00:02:14,640 --> 00:02:17,060 or whatever in the original document. 41 00:02:17,060 --> 00:02:21,810 Next, another corona wire creates a stronger negative charge in the paper that is to receive 42 00:02:21,810 --> 00:02:27,480 the toner, and this stronger charge will attract the toner off of the of drum and onto the paper. 43 00:02:27,480 --> 00:02:32,080 And finally the paper, now covered in powder, goes through the fuser unit, which melts this 44 00:02:32,080 --> 00:02:35,959 powder to the paper, and thus a stable photocopy is made. 45 00:02:35,959 --> 00:02:40,380 Fast forward to the late 1960’s, and Gary Starkweather, an engineer from Xerox’s product 46 00:02:40,380 --> 00:02:45,140 division, had the idea of using a laser beam to draw directly onto the imaging drum of 47 00:02:45,140 --> 00:02:46,670 a photocopier. 48 00:02:46,670 --> 00:02:51,440 With computer control, you could draw text and images directly on the drum with the laser, 49 00:02:51,440 --> 00:02:53,180 thus turning it into a printer. 50 00:02:53,180 --> 00:02:54,900 And that’s exactly what happened. 51 00:02:54,900 --> 00:02:59,360 Using a laser diode, lenses, and a spinning mirror, laser printers draw onto the drum 52 00:02:59,360 --> 00:03:03,240 in lines, and the laser is pulsed on and off to create the image. 53 00:03:03,240 --> 00:03:07,160 The resolution of the printer is determined by the number of lines it can draw in a given 54 00:03:07,160 --> 00:03:11,110 unit, in addition to the maximum number of times the laser can be pulsed on or off within 55 00:03:11,110 --> 00:03:12,450 that line. 56 00:03:12,450 --> 00:03:16,920 Often the resolution is measured in dots per inch, so a printer with 600 dpi will scan 57 00:03:16,920 --> 00:03:22,220 the drum 600 times along the length of one inch, and the laser can pulse on and off 600 58 00:03:22,220 --> 00:03:27,790 times within one inch of each line, meaning each square inch has 600 by 600 discrete points 59 00:03:27,790 --> 00:03:31,300 that can be either on or off--that is, black or white. 60 00:03:31,300 --> 00:03:36,180 Incidentally, this method of creating an image using lines of light is strikingly similar 61 00:03:36,180 --> 00:03:38,440 to how analog television works. 62 00:03:38,440 --> 00:03:42,099 I made a series on television if you’d like to check it out, but the pattern is called 63 00:03:42,099 --> 00:03:43,300 a raster. 64 00:03:43,300 --> 00:03:48,480 Raster scanning in laser printers requires that the entire image, in its full resolution, 65 00:03:48,480 --> 00:03:51,240 be loaded into its memory before printing can commence, 66 00:03:51,240 --> 00:03:53,430 as it has to be done in one shot. 67 00:03:53,430 --> 00:03:58,420 It can’t start and stop like an inkjet printer, particularly because the fuser unit is liable 68 00:03:58,420 --> 00:04:03,860 to burn some paper (or at least singe it a litte) if it were to suddenly stop mid-print. 69 00:04:03,860 --> 00:04:05,380 So, laser printing works. 70 00:04:05,380 --> 00:04:07,090 And it works really well! 71 00:04:07,090 --> 00:04:11,900 But the actual laser mechanism is kinda big, and relying on a spinning thing to make the 72 00:04:11,900 --> 00:04:15,489 image introduces more moving parts and complexity. 73 00:04:15,489 --> 00:04:17,709 And that’s where the LED printer comes in. 74 00:04:17,709 --> 00:04:18,769 When did it come in? 75 00:04:18,769 --> 00:04:19,909 And who invented it? 76 00:04:19,909 --> 00:04:21,079 I’m not sure. 77 00:04:21,079 --> 00:04:25,639 It’s a weird footnote into the development of the laser printer, but Oki claims to have 78 00:04:25,640 --> 00:04:29,000 made the world’s first LED printer in 1981. 79 00:04:29,000 --> 00:04:33,699 It’s surprising how little info there seems to be about LED printers, though as we’ll 80 00:04:33,699 --> 00:04:35,729 see, perhaps that’s to be expected. 81 00:04:35,729 --> 00:04:37,580 What makes LED printers different? 82 00:04:37,580 --> 00:04:42,420 Well, rather than use a scanning laser, LED printers use LEDs. 83 00:04:42,520 --> 00:04:43,400 Shocking. 84 00:04:43,480 --> 00:04:48,919 But in a unique way--this Brother HL-3040CN is a color LED printer. 85 00:04:48,919 --> 00:04:54,180 If I lift on the lid, you’ll see these four bars here that kinda flip out of the way when 86 00:04:54,180 --> 00:04:56,520 the lid’s all the way up. 87 00:04:56,520 --> 00:05:00,710 There are four because this is a color printer--one each for cyan, magenta, yellow, and black 88 00:05:00,710 --> 00:05:03,550 (more correctly referred to as key). 89 00:05:03,550 --> 00:05:05,539 These bars are the key. 90 00:05:05,539 --> 00:05:09,599 Each of these things is an array of tiny individual LEDs. 91 00:05:09,599 --> 00:05:13,830 Each LED handles one column of pixels--or dots--on the page. 92 00:05:13,830 --> 00:05:18,930 This printer has a resolution of 600 DPI, so along this entire bar there are roughly 93 00:05:18,930 --> 00:05:20,759 5,000 LEDs. 94 00:05:20,759 --> 00:05:25,029 If you look closely you’ll see a pattern of dots--these are lenses that focus the light 95 00:05:25,029 --> 00:05:29,050 from multiple LEDs behind them onto the correct spot of the drum. 96 00:05:29,050 --> 00:05:33,630 The LEDs themselves are so small as to be nearly invisible to the naked eye. 97 00:05:33,630 --> 00:05:37,280 Below these assemblies lie individual drum and toner cartridges. 98 00:05:37,280 --> 00:05:41,870 You can see that when the lid is closed, the LED bar sits right on top of the drums. 99 00:05:41,870 --> 00:05:45,379 You’ll also find evidence of toner mishaps, but, ehhh. 100 00:05:45,379 --> 00:05:50,620 So when this printer prints, rather than spinning a mirror and pulsing a laser on and off, each 101 00:05:50,620 --> 00:05:53,490 LED simply pulses on its own. 102 00:05:53,490 --> 00:05:58,839 As the print drum rotates, the LEDs will flash when they need to, and stay dark when they don’t. 103 00:05:58,839 --> 00:06:03,849 There are many times as many light sources--in fact thousands of times--compared to a laser 104 00:06:03,849 --> 00:06:08,460 printer, but the lack of a mechanical component, plus the direct physical alignment of the 105 00:06:08,460 --> 00:06:13,020 LEDs with the drum, means that LED printers might be more reliable. 106 00:06:13,020 --> 00:06:15,060 And they certainly are more compact. 107 00:06:15,060 --> 00:06:17,259 Particularly with color printers. 108 00:06:17,259 --> 00:06:21,409 Notice how this printer has each color of toner simply in a row. 109 00:06:21,409 --> 00:06:25,129 Because there’s no need for a complicated optical system, this printer is essentially 110 00:06:25,129 --> 00:06:28,350 just 4 printers lined up in one case. 111 00:06:28,350 --> 00:06:33,270 And if I pull one of these out, you’ll see how small the toner and drum cartridges are. 112 00:06:33,270 --> 00:06:37,180 Yes compared to an injket these are laughably big, but for a toner-based printer this is 113 00:06:37,180 --> 00:06:38,969 actually pretty small. 114 00:06:38,969 --> 00:06:44,789 This design also gives color LED printers a huge advantage compared to laser--speed. 115 00:06:44,789 --> 00:06:48,559 To convert from black and white to color, this printer essentially just takes the printer 116 00:06:48,559 --> 00:06:51,710 part, then Ctrl-C Ctrl-V’s it a few times. 117 00:06:51,710 --> 00:06:56,960 The paper travels in a straight path as it gets black, yellow, magenta, and finally cyan toners. 118 00:06:56,960 --> 00:06:58,789 Then it’s fused on its way out. 119 00:06:58,789 --> 00:07:02,759 Color LED printers used to boast that their printing speeds were nearly the same between 120 00:07:02,759 --> 00:07:04,689 color and black and white. 121 00:07:04,689 --> 00:07:09,160 Many color laser printers, such as this one from Samsung, print at a fraction of their 122 00:07:09,160 --> 00:07:13,300 black and white speeds, because when printing in color, the paper has to take a meandering 123 00:07:13,300 --> 00:07:16,199 path through four printing assemblies. 124 00:07:16,199 --> 00:07:20,529 With setups like this from Brother, it’s just boom boom boom boom, fuse the toner, 125 00:07:20,529 --> 00:07:21,529 and we’re done. 126 00:07:21,529 --> 00:07:24,740 Now, laser printers do still have their advantages over LED. 127 00:07:24,740 --> 00:07:28,830 It’s easier to achieve a higher resolution when you have the benefit of motion, rather 128 00:07:28,830 --> 00:07:31,660 than relying on smaller and smaller LEDs. 129 00:07:31,660 --> 00:07:36,499 Plus, apparently LED printers can have less consistent images due to slight variations 130 00:07:36,500 --> 00:07:38,280 between each LED. 131 00:07:38,280 --> 00:07:41,960 I can’t say whether I’ve noticed that in person, but this paper from Xerox sure 132 00:07:41,960 --> 00:07:43,559 is trying to convince me. 133 00:07:43,559 --> 00:07:45,599 But here’s the kinda humorous bit. 134 00:07:45,599 --> 00:07:49,959 I’m willing to wager that many “laser printers” available on the market are in 135 00:07:49,959 --> 00:07:53,789 fact LED printers, but they’re just not so clearly labeled. 136 00:07:53,789 --> 00:07:58,029 Poking around on Amazon I found plenty of printers that don’t have much of a difference 137 00:07:58,029 --> 00:08:02,400 between their color and black and white speeds, and some printers like this Canon have the 138 00:08:02,400 --> 00:08:07,280 toner arranged suspiciously similarly to this Brother printer. 139 00:08:07,280 --> 00:08:11,339 And Brother is definitely still using LED printing technology, as evidenced by this 140 00:08:11,339 --> 00:08:13,839 picture on this Amazon listing. 141 00:08:13,839 --> 00:08:18,469 To their credit, they simply call it a “digital color printer” and it’s Amazon that’s 142 00:08:18,469 --> 00:08:20,960 labeling it as “laser printer technology”. 143 00:08:20,960 --> 00:08:25,660 Anyway, maybe this Canon is a real laser printer, and they’re just packaging the laser scanners 144 00:08:25,660 --> 00:08:29,169 more efficiently so that the paper can pass in a straight line. 145 00:08:29,169 --> 00:08:33,030 But there are still some color laser printers on the market that print fast in black and 146 00:08:33,030 --> 00:08:36,160 white and at a leisurely pace for color. 147 00:08:36,160 --> 00:08:39,940 The Samsung unit we looked at earlier prints at a respectable 19 pages per minute black 148 00:08:39,940 --> 00:08:44,510 and white, but only 4 ppm color. 149 00:08:44,510 --> 00:08:46,720 Not so “Xpress”, after all. 150 00:08:46,760 --> 00:08:50,780 In any case, I think that it’s a shame how little is known about the LED printer. 151 00:08:50,780 --> 00:08:53,690 Sure, on the surface, it’s just a laser printer. 152 00:08:53,690 --> 00:08:58,440 An LED printer will produce near identical results, and behave in a near-identical fashion. 153 00:08:58,440 --> 00:09:03,380 It’s still a drum and toner system--how the image gets to the drum is arguably trivial. 154 00:09:03,380 --> 00:09:05,600 But I think it’s a clever way to handle it. 155 00:09:05,600 --> 00:09:08,460 Thanks for watching this (for this channel anyway) quick video. 156 00:09:08,460 --> 00:09:11,911 I’ve interrupted the series on the compact disc to bring you this video and we’ll be 157 00:09:11,911 --> 00:09:14,010 resuming where we left off soon. 158 00:09:14,010 --> 00:09:18,120 As always, thank you to those supporting Technology Connections on Patreon. 159 00:09:18,120 --> 00:09:21,080 Patrons of the channel are what keep these videos coming, and if you’d like to make 160 00:09:21,080 --> 00:09:24,180 a pledge to the channel, please check out my Patreon page. 161 00:09:24,180 --> 00:09:26,800 Thank you for your consideration, and I’ll see you next time!