WEBVTT Kind: captions Language: en 00:00:00.080 --> 00:00:01.820 Today’s video is about printers. 00:00:01.820 --> 00:00:06.080 I know, you’re probably filled with excitement at the mere mention of printers, but please 00:00:06.080 --> 00:00:07.560 remain calm. 00:00:07.560 --> 00:00:11.350 If you were to go shopping for a printer, you’ll almost certainly find yourself choosing 00:00:11.350 --> 00:00:14.549 between an inkjet printer and a laser printer. 00:00:14.549 --> 00:00:17.960 Or perhaps a 3D printer, but we’re not talking about those today. 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 00:00:21.630 --> 00:00:25.369 anything but photo printing because that’s not really the point of this video. 00:00:25.369 --> 00:00:28.783 Instead, we’re going to talk about a subset of the laser printer 00:00:28.783 --> 00:00:31.370 that seems to fly under the radar. 00:00:31.370 --> 00:00:32.900 The LED printer. 00:00:32.900 --> 00:00:35.500 Now, if you’ve never heard of this before I wouldn’t blame you. 00:00:35.500 --> 00:00:39.160 Fundamentally LED printers are the same as a laser printer. 00:00:39.160 --> 00:00:41.910 They still use powdered toner rather than liquid ink. 00:00:41.910 --> 00:00:46.530 They use photosensitive drums to transfer toner to paper (along with corona wires and/or 00:00:46.530 --> 00:00:49.370 other charge inducing or destroying doodads). 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 00:00:54.220 --> 00:00:57.340 is nice and warm, just asking you to give it a hug. 00:00:57.340 --> 00:01:01.110 But where they differ is in how the image is drawn on the drum. 00:01:01.110 --> 00:01:04.910 And to understand why that’s important, let’s have a quick lesson into how laser 00:01:04.910 --> 00:01:07.000 printing works and how it came about. 00:01:07.000 --> 00:01:10.840 Laser printers are essentially an offshoot of the photocopier. 00:01:10.840 --> 00:01:15.340 Using a process called xerography, which comes from the Greek for dry writing (and now you 00:01:15.340 --> 00:01:21.000 know where Xerox got its name), analog photocopiers use a cylindrical drum coated in a photoconductive 00:01:21.000 --> 00:01:22.310 material. 00:01:22.310 --> 00:01:25.970 This material becomes conductive when exposed to light. 00:01:25.970 --> 00:01:30.240 To duplicate the image, the drum is first charged by a corona wire, which produces a 00:01:30.240 --> 00:01:33.390 high voltage and gives the drum a static charge. 00:01:33.390 --> 00:01:37.570 The now negatively charged drum is rolled underneath a piece of paper to be copied, 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 00:01:42.250 --> 00:01:43.820 illumination. 00:01:43.820 --> 00:01:48.260 Because the photoconductive material will conduct electricity when exposed to light, 00:01:48.260 --> 00:01:53.340 any bright areas become discharged, as a path to ground can now be completed. 00:01:53.340 --> 00:01:56.320 Dark areas, where printing or handwriting exist on the original, 00:01:56.320 --> 00:01:58.490 will remain negatively charged. 00:01:58.490 --> 00:02:03.510 This drum is then rolled against a supply of powdered toner, which is positively charged. 00:02:03.510 --> 00:02:07.780 This toner will thus want to stick to any areas of the drum that remained negatively 00:02:07.780 --> 00:02:10.320 charged from the original exposure. 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 00:02:14.640 --> 00:02:17.060 or whatever in the original document. 00:02:17.060 --> 00:02:21.810 Next, another corona wire creates a stronger negative charge in the paper that is to receive 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. 00:02:27.480 --> 00:02:32.080 And finally the paper, now covered in powder, goes through the fuser unit, which melts this 00:02:32.080 --> 00:02:35.959 powder to the paper, and thus a stable photocopy is made. 00:02:35.959 --> 00:02:40.380 Fast forward to the late 1960’s, and Gary Starkweather, an engineer from Xerox’s product 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 00:02:45.140 --> 00:02:46.670 a photocopier. 00:02:46.670 --> 00:02:51.440 With computer control, you could draw text and images directly on the drum with the laser, 00:02:51.440 --> 00:02:53.180 thus turning it into a printer. 00:02:53.180 --> 00:02:54.900 And that’s exactly what happened. 00:02:54.900 --> 00:02:59.360 Using a laser diode, lenses, and a spinning mirror, laser printers draw onto the drum 00:02:59.360 --> 00:03:03.240 in lines, and the laser is pulsed on and off to create the image. 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 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 00:03:11.110 --> 00:03:12.450 that line. 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 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 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 00:03:27.790 --> 00:03:31.300 that can be either on or off--that is, black or white. 00:03:31.300 --> 00:03:36.180 Incidentally, this method of creating an image using lines of light is strikingly similar 00:03:36.180 --> 00:03:38.440 to how analog television works. 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 00:03:42.099 --> 00:03:43.300 a raster. 00:03:43.300 --> 00:03:48.480 Raster scanning in laser printers requires that the entire image, in its full resolution, 00:03:48.480 --> 00:03:51.240 be loaded into its memory before printing can commence, 00:03:51.240 --> 00:03:53.430 as it has to be done in one shot. 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 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. 00:04:03.860 --> 00:04:05.380 So, laser printing works. 00:04:05.380 --> 00:04:07.090 And it works really well! 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 00:04:11.900 --> 00:04:15.489 image introduces more moving parts and complexity. 00:04:15.489 --> 00:04:17.709 And that’s where the LED printer comes in. 00:04:17.709 --> 00:04:18.769 When did it come in? 00:04:18.769 --> 00:04:19.909 And who invented it? 00:04:19.909 --> 00:04:21.079 I’m not sure. 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 00:04:25.640 --> 00:04:29.000 made the world’s first LED printer in 1981. 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 00:04:33.699 --> 00:04:35.729 see, perhaps that’s to be expected. 00:04:35.729 --> 00:04:37.580 What makes LED printers different? 00:04:37.580 --> 00:04:42.420 Well, rather than use a scanning laser, LED printers use LEDs. 00:04:42.520 --> 00:04:43.400 Shocking. 00:04:43.480 --> 00:04:48.919 But in a unique way--this Brother HL-3040CN is a color LED printer. 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 00:04:54.180 --> 00:04:56.520 the lid’s all the way up. 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 00:05:00.710 --> 00:05:03.550 (more correctly referred to as key). 00:05:03.550 --> 00:05:05.539 These bars are the key. 00:05:05.539 --> 00:05:09.599 Each of these things is an array of tiny individual LEDs. 00:05:09.599 --> 00:05:13.830 Each LED handles one column of pixels--or dots--on the page. 00:05:13.830 --> 00:05:18.930 This printer has a resolution of 600 DPI, so along this entire bar there are roughly 00:05:18.930 --> 00:05:20.759 5,000 LEDs. 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 00:05:25.029 --> 00:05:29.050 from multiple LEDs behind them onto the correct spot of the drum. 00:05:29.050 --> 00:05:33.630 The LEDs themselves are so small as to be nearly invisible to the naked eye. 00:05:33.630 --> 00:05:37.280 Below these assemblies lie individual drum and toner cartridges. 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. 00:05:41.870 --> 00:05:45.379 You’ll also find evidence of toner mishaps, but, ehhh. 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 00:05:50.620 --> 00:05:53.490 LED simply pulses on its own. 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. 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 00:06:03.849 --> 00:06:08.460 printer, but the lack of a mechanical component, plus the direct physical alignment of the 00:06:08.460 --> 00:06:13.020 LEDs with the drum, means that LED printers might be more reliable. 00:06:13.020 --> 00:06:15.060 And they certainly are more compact. 00:06:15.060 --> 00:06:17.259 Particularly with color printers. 00:06:17.259 --> 00:06:21.409 Notice how this printer has each color of toner simply in a row. 00:06:21.409 --> 00:06:25.129 Because there’s no need for a complicated optical system, this printer is essentially 00:06:25.129 --> 00:06:28.350 just 4 printers lined up in one case. 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. 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 00:06:37.180 --> 00:06:38.969 actually pretty small. 00:06:38.969 --> 00:06:44.789 This design also gives color LED printers a huge advantage compared to laser--speed. 00:06:44.789 --> 00:06:48.559 To convert from black and white to color, this printer essentially just takes the printer 00:06:48.559 --> 00:06:51.710 part, then Ctrl-C Ctrl-V’s it a few times. 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. 00:06:56.960 --> 00:06:58.789 Then it’s fused on its way out. 00:06:58.789 --> 00:07:02.759 Color LED printers used to boast that their printing speeds were nearly the same between 00:07:02.759 --> 00:07:04.689 color and black and white. 00:07:04.689 --> 00:07:09.160 Many color laser printers, such as this one from Samsung, print at a fraction of their 00:07:09.160 --> 00:07:13.300 black and white speeds, because when printing in color, the paper has to take a meandering 00:07:13.300 --> 00:07:16.199 path through four printing assemblies. 00:07:16.199 --> 00:07:20.529 With setups like this from Brother, it’s just boom boom boom boom, fuse the toner, 00:07:20.529 --> 00:07:21.529 and we’re done. 00:07:21.529 --> 00:07:24.740 Now, laser printers do still have their advantages over LED. 00:07:24.740 --> 00:07:28.830 It’s easier to achieve a higher resolution when you have the benefit of motion, rather 00:07:28.830 --> 00:07:31.660 than relying on smaller and smaller LEDs. 00:07:31.660 --> 00:07:36.499 Plus, apparently LED printers can have less consistent images due to slight variations 00:07:36.500 --> 00:07:38.280 between each LED. 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 00:07:41.960 --> 00:07:43.559 is trying to convince me. 00:07:43.559 --> 00:07:45.599 But here’s the kinda humorous bit. 00:07:45.599 --> 00:07:49.959 I’m willing to wager that many “laser printers” available on the market are in 00:07:49.959 --> 00:07:53.789 fact LED printers, but they’re just not so clearly labeled. 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 00:07:58.029 --> 00:08:02.400 between their color and black and white speeds, and some printers like this Canon have the 00:08:02.400 --> 00:08:07.280 toner arranged suspiciously similarly to this Brother printer. 00:08:07.280 --> 00:08:11.339 And Brother is definitely still using LED printing technology, as evidenced by this 00:08:11.339 --> 00:08:13.839 picture on this Amazon listing. 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 00:08:18.469 --> 00:08:20.960 labeling it as “laser printer technology”. 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 00:08:25.660 --> 00:08:29.169 more efficiently so that the paper can pass in a straight line. 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 00:08:33.030 --> 00:08:36.160 white and at a leisurely pace for color. 00:08:36.160 --> 00:08:39.940 The Samsung unit we looked at earlier prints at a respectable 19 pages per minute black 00:08:39.940 --> 00:08:44.510 and white, but only 4 ppm color. 00:08:44.510 --> 00:08:46.720 Not so “Xpress”, after all. 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. 00:08:50.780 --> 00:08:53.690 Sure, on the surface, it’s just a laser printer. 00:08:53.690 --> 00:08:58.440 An LED printer will produce near identical results, and behave in a near-identical fashion. 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. 00:09:03.380 --> 00:09:05.600 But I think it’s a clever way to handle it. 00:09:05.600 --> 00:09:08.460 Thanks for watching this (for this channel anyway) quick video. 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 00:09:11.911 --> 00:09:14.010 resuming where we left off soon. 00:09:14.010 --> 00:09:18.120 As always, thank you to those supporting Technology Connections on Patreon. 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 00:09:21.080 --> 00:09:24.180 a pledge to the channel, please check out my Patreon page. 00:09:24.180 --> 00:09:26.800 Thank you for your consideration, and I’ll see you next time!