Printronix Thermal Bar Code Printer Overview
In this post we review our thermal bar code printer product family. We go in depth as Product Marketing Director Andy Scherz explains how thermal bar code printers work. In addition to explaining key differences between direct thermal and thermal transfer technology. Andy also explains what applications are more appropriate for thermal resin ribbons or thermal wax ribbons and which applications are more appropriate for thermal transfer bar code printers.
Thermal Transfer Ribbons Vs. Direct Thermal Ribbons
So what is a thermal printer? Let me give you a little bit of the background on what the technology behind a thermal printer is. It's a fairly simple mechanism, you've got your paper, that's going to be the label that you're going to print on, and then you have a ribbon, and this ribbon is a, like a big long clear piece of mylar, like a thin plastic ribbon with wax or resin or various types of coatings on one side of it. Then you have a printhead that goes in and I've shown this thing kind of exploded but in the printer these three things are all pressing together, and very simply you apply power to an individual dot on that printhead and it gets hot, much like when you switch on a light bulb, the lightbulb gets hot ok.
We use that heat and it actually melts the image, melts the wax or resin, pulls it off the mylar onto the media making an indelible spot. Therein goes the name, thermal transfer, meaning you're using heat to transfer from the ribbon to the page. It makes a very durable image because what you're putting on the page might be a piece of plastic or a piece of very durable wax that can make a highly durable image, and that's why thermal transfer became very popular. If you see it thermal transfer label, you notice that it has a really stunning black contrast and it's because unlike just sort of writing on it, or printing with a little bit of ink you've really built almost a three-dimensional thick black image on top of the paper.
But that's not the only way to make an image using a thermal printer, there's an alternate method that's called direct thermal, and printronix printers do both. So what's the difference between a direct thermal and the thermal transfer printer? A thermal printer is basically the same thing but there's no termal wax or thermal resin ribbon.
What is used instead is you put a heat sensitive coating on top of the paper, it looks like plain paper to the naked eye, but in reality there's a coating on the paper. So we have the same basic principle, you apply electricity to the printhead element, it creates heat that this media is thermally sensitive so it creates an image when it reacts with the heat and the result is a direct thermal image.
Well then which one is better? There's really no such thing as which one is better okay? They are both popular, and they both have their place, and as I described in the below table where I illustrate the stronger attributes in green, and the weaker attributes in red. What are the differences?
The head life for example, that printhead I showed you, it's rubbing right on the paper, and you kind of know, if you've got paper cuts and things before, paper is fairly abrasive, it will wear the head out quickly. So, the thermal transfer is better because that ribbon has that smooth mylar and lasts longer.
If you've ever had a receipt from Home Depot for example, and left it up on the dashboard of your car, when you come back two hours later you can hardly read it because the sun baked onto that receipt. That was a direct thermal image, and sometimes that media can be subject to fading due to light or heat or other things like that, not quite as durable. So maybe if I'm making a part label I'm going to go with thermal transfer labels. On the other hand, direct thermal is so easy, you just slap paper in and magically it goes, there's no ribbon and nothing to line up, it's really easy. You've all probably seen the cash register, open the printer, put a roll of paper in there, slap the hatch and you're ready to go, that's part of the simplicity of direct thermal.
The image contrast I told you of burning that bright waxy image on there makes a real high contrast, not as sharp on the direct thermal.
But of course if you're buying thermal transfer ribbons you are paying a little more, but then the media is cheaper because it doesn't have a coating on it.
In mobile printing you normally don't see thermal transfer, you mostly see direct thermal for mobile receipt printers.
Flexibility of substrates
What you're printing on, obviously if I have to use some specially coated paper I don't have the same range of of substrates, you'll find that when you look at some other label types you'll see there's substrate, it means what you're going to be putting a label on, it's real important.
Another way to look at the market here is to look at how the market is split that way, and this is sort of an aggregate view of all thermal printing.
You see about 41% direct thermal compared to 59% thermal transfer. And it's largely centered around the type of application you doing. Things like receipts event wristbands are seen more so on direct thermal, but a lot of the labels you might see likely permanent asset label, a permanent shipping label, something like that would be done with thermal transfer.
For more information on Printronix thermal transfer and direct thermal bar code printing solutions, visit our thermal printer page on our web site. For more information on thermal transfer resin ribbons more information can be found on ours printer supplies page.