How Printers Work

an old daisy wheel printer. I have one. Well, yeah, that'll uh, I'll get swept up immediately on eBay. Yeah. Well, we were going to talk about printers today, down about different kinds of printers and how they work. And uh, I actually do, indeed have a daisy wheel printer at home, which is basically a typewriter. For those of you who are too young to remember what a typewriter is, it basically is a keyboard at type to a printer directly

talk about your wireless printers. Uh, you know that that's about as wireless as it gets. But early printers used a wheel with the letters printed in metal. Uh, sort of reverse type and it would you know, as you typed. Uh. This the one I've got actually has a keyboard that hooks up to it. If you didn't have a computer yet, uh, and you could actually print it out, it would it would.

The daisy wheel spins and it literally does look sort of like a metallic daisy because it each key has its own pin and it goes and hits the ribbon and you know, types out a letter for you the paper that transfers the ink to the paper and woila, you have the printed word. There you go and uh, it's it's about as simple, I guess a printer as you can get in one of the earliest types. But

you don't see them very often anything. No, Gully, I can't imagine why my my father has a dot matrix printer still at his house, which serves as a great paper weight. Um, because they're quite heavy. Dot matrix are similar. That's a Uh. These are the kind of printers we're talking about right now, are impact printers, meaning that they there's a physical impact that uh that where something contacts the sheet of paper and that's what makes the the

printed letter. With dot matrix, it's a series of pins that that when they strike the ribbon, that's what forms the letters. So they don't have each letter laid out on a on a metal sheet or anything like that. It's just little tiny pins that all hit at the same time. So um, yeah, you don't see many of those anymore either. These are not also these if you have ever used one of these, they have a very

distinctive sound. Um and they also the paper tended to be pretty annoying too, as I recall, most of them were in those long, long, long sheets where you'd have to tear it off at the end with the green and yellow stripes with the right perforated the perforated edges where it with the holes that would go into Yeah, exactly, that was Those were nightmare to work with, trust me. Although you could make some nice origami with the stuff that you had to tear off those papers. But but

but that's that's sort of in the past. Or there's still lots of industries that use impact printers because they're relatively inexpensive and and uh, you know, they last for a pretty long time. You do have to do maintenance on them. But most people have moved to non impact printers, and the two main versions of that. The two one to that you find most in the in the UH consumer market and even in the office environment are ink jet printers and laser printers. Right, yeah, yeah, pretty much.

I mean there there are other types to uh. In fact, I'll go ahead and run through them so we can get them out of the way, so other forms of non impact printers. I kind of wish we had like background music for this. Who knows, maybe our producer Jerry will figure something out, so we'll have a little little mood to here to set up the atmosphere. Actually, I've I've prepared a power point so if you could all imagine what it looks like as you are listening to

us talk, and you know that it's beautiful. It's absolutely beautiful. It's it is stunning. I don't know how he got this color saturation, tell you the truth. But um, let's start with all right, we have a solid ink printers um, which I think you are going to talk about a little bit later because you have some sort of weird fascination with solid ink. Yeah. Well, it's just one of those things that's sort of really cool. Anyway, you were going to talk about kind of prints. We'll go back

to it all right. You have the die sublimation printers, which uses transparent film to transfer ink to paper. Um, that uses a heat to do that. Um. There's thermal wax printers, which are kind of the combination of die sublimation and solid inc You've got thermal autochrome printers, and that's where you have the ink in the paper already and you just use heat to make the income to

make letters visible. So these are your other forms. Now, those are kind of they make up a minority of all the non impact printers that are on the market. Like I said, the two biggies are ink jet and laser printers. Now, did you want to talk about solid ink before we move on? Well, you know, solid ink is fascinating to me simply because, uh, you know, it's

it's actually pretty simple. Um, when you're loading your and then we're talking about color printers here, so it's not just you know, black, you can actually use a color printer and instead of putting in a plastic cartridge filled with a liquid ink or putting powdered toner in like you were with an ink jet or a laser respectively. Um, you actually use a block of solid ink it's sort of it sort of looks like a giant square crayon, or some of them aren't even square. Um, this is

a Xerox thing. I mean, it's it's Xerox's baby there as far as I know. The only ones who actually manufacture these, um, but they're pretty cool. They don't use any cartridges. What it does is essentially it it melts um this resin based non toxic ink uh and use the uh. The ink it goes on the print head, which transfers it onto the print drum. So when the paper goes through the printer, the print drum actually transfers

the image onto their using heat and pressure. So that's that's kind of a different technique to uh, you know, spraying it, which was which is what you do with ink jetsing jet printers make you know, complete sense from hearing your name. It's a jet of ink being sprayed onto the paper to make letters or pictures or whatever. It is, right, and um, it's it's a spray that's very very fine, a very fine spray. The the drops are tend to be between fifty and sixty microns in diameter,

so that's pretty small human hair. Something I don't know much about is about the diameter of seventy microns umpholically challenged. But yeah, so so these are very tiny dots that that come out in in really fast bursts, so several bursts per second. I mean, it's it's it's remarkably fast. In fact, it's so fast that that to us usually if you see a piece of paper going into an inkjet printer, a good inkjet printer, it looks like it's

constantly moving. It's really starting and stopping, but it's doing it at such a high speed that it it looks like it's a constant movement. But yeah, you have all these little tiny nozzles in an ink jet printer that that emit the ink, and um they do it in a couple of different ways. Um so, but that's that's the basic principle behind it. Eventually, the the when the paper comes out, the ink dries, uh and you've got your your printed page. As opposed to say the solid

inc format where you actually let the ink cool. It's it's almost like like a candle, like if you melted the candle and then let the wax cool and it solidifies again. That's sort of the the way solid ink works, whereas the ink jet type stuff it it just kind

of dries. So that's what you end up with the letters on the page speaking of which is not the kind of thing you want to get wet, right, because speaking from personal experience, if you are working on something and you like a spill your coffee on it or something or glass water, you're pretty much going to ruin

an ink jet printed page. I think they've gotten. It depends on paper and and things that you know, depending on how well it soaks in, and of course, depending on how well it soaks in, you can really splotchy pages just from the ink jet printing on it. Early ink jet that was bad about that. I had to use a certain quality of paper with a certain amount of clay content for it to actually show up and not uh completely seep in and make a giant blob in the middle of the page. Yeah, you can see

that in even high quality printers. If you don't, if you don't maintain them and clean them often enough, then you're going to have some some smearing issues. With ink jets, the nozzles can clog to exact problems. And there's two different two different kinds of of nozzles. We might as well those as well. There's the thermal bubble nozzle, which

of course bubble jet right exactly. The bubble jet for the subset of the ink jet family creates a small bubble with the bubble burst that creates a vacuum, draws in through the nozzles, sprays on the paper. Really exciting science stuff. The other one is even more science if you can believe it. Settle yourself here it goes the piezo electric crystal method um. Now, piece of electric crystal.

That's the kind of crystal that if you run an electric charge through it, it changes shape and vice versa. If you change the shape of the crystal, it emits an electric charge. These are the sort of crystals that are in things like like like watches to keep time because they're they're very they're very predictable. You know, depending on the material you're talking about, you can you know exactly how it's going to change shape depending on how

much of an electrical charge you pass through it. So in this case, these crystals kind of act as a valve for the nozzle and as the printer runs an electric charge through it, it it allows inc to pass through or blocks inc from passing through and that's how those work. So, um, I guess we can move on over to the most dangerous printer in the world, the laser jet laser printer. These also use UH positive and negative electrical charges to help with the printing process. Um i've i've actually a

little uncertain as too much charge. But the initially the drum inside the printer, which is a smaller version of the one you might see if you watch a video about how they make UH newspapers or magazines. You see these giant H drums rotating on a press. Well, there's a smaller version of that inside your the laser printer sitting on your desk or you know, down the hall

at your at your workplace. And basically they charge the drum and put toner on the drum and a laser passes over it and when the paper goes through, it gets the opposite electrical charge and that helps transfer the image onto the paper. Right, the laser just provides the the correct charge to the right spots on the toner, so that way the toner that has charged that way will will transfer. All the rest of the toner won't transfer, because otherwise all you would end up with is you know,

sheet completely covered in toner. So it's kind of neat that they're using lasers to do this. That it's this this really precise way to um to transfer inc from the drum onto the page. And then after the that that goes on the drum rotates another lamp, a very powerful lamp is shown on the drum itself, which clears the charge, so it prepares it for the next page. Because if you didn't do that, then you would end

up with ghost images of previous pages. So you would end up seeing like everything on page page two, you would start to see a little ghost images of stuff from page one, and then page three, the page one images would be slightly lighter, but then you'd also have the page two and it would be a big mess. So you have to have a way to clear the drum after each sheet, and that's how they do it. They use this um this lamp to to to clear it.

And then as one last step before the page leaves the printer, it goes through what's called a fuser, which essentially melds the I really wanted to use the word meld um. That melds the toner on into the paper fibers, so basically it you know, fuses it together, glues it together on there, so it appears in those letters until you put it in a vinyl notebook, leave it there for a while, then peel it off to find all the dinner and stuck on the vinyl, and now you

have it when your notebook and reverse. Wow again. I know this from personal experience. I was detecting a little note of bitterness in that which one is better for which? What? If you if you're looking for crisp colors, if you're looking for speed, you know what which printer is best for which application? In general, I think laser printers tend to be the fastest. Um. They're the you're they're usually

faster than your ink jets. Uh. Although if you're printing a lot um and you're printing in a hurry, you should also be careful because those pages come out awfully hot from the user. If you're if you're running a pretty powerful printer, I speak from personal experience of the press, Yes exactly, it is literally hot off the press. You can you could actually scort yourself a little. Um. Now, the paper is moving really fast with the fuser, so

it won't. It won't normally scort, unless, of course, something has gone horribly wrong with your laser printer, in which case that could theoretically happen. Um. But yeah, I seem to I find laser printers to be to be the best if you're looking for something like a high quantity print job. If you're printing something that's like, say you're printing reports, and you're printing out a hundred reports, and each reports sporting pages long, a laser printer is gonna

do it a lot faster than an ink jet. Um or your local copy center, Well, your local copy center is very likely using a laser printer, so so it's still the same. I doubt that they've got the Guttenberg press back there, so um, so I would go with laser most of the time. I mean now, granted, for my own personal use, I have an ink jet because I don't tend to do high volume print jobs, so it's and a jet. The qualities nice. Uh um. The

cartridges aren't too terribly expensive, so that's what I stick with. Yeah, they can. That's what you find for your your photo printers, your digital photo printers, exact. The quality of the images is considerably better. Well, I think we've we've we're all printed out. I think we should we should lay this one to bed. So, if you guys want to learn more about printers, you should read how inkjet printers work and how Laser printers Work, both of which are live

right now on how stuff works dot com. I didn't even know Steve Gutenberg had a prints. I'm gonna hit you so hard. Let us know what you think. Send an email to podcast and how stuff works dot com, brought to you by the reinvented two thousand twelve camera. It's ready, are you