Gamma Electronics Blog
What is a Thermal Printer?
You may not be aware of it, but you likely encounter thermal printers on a near daily basis. Thermal printers print out some of our most printed items like receipts, packaging labels, cable labels, and more. So, what are thermal printers, what makes them different, and why are they so commonly used?
What is a Thermal Printer?
A thermal printer utilizes heat to print. Most thermal printers work with a special, chemical paper that when heated, changes color. Other types of thermal printers, (more often referred to as thermal transfer printers), have a unique printer ribbon that, when heated, can transfer the resin of the ribbon onto another material, (like heat shrink tubing). No matter what type of thermal printer you are using they all utilize heat to print, (hence the term “thermal” in the name),
How Does a Thermal Printer Work?
As stated above, most thermal printers utilize a chemical paper that, when heated, changes color. The job of the printer however is not just to heat the paper, but to selectively heat the parts of the paper you want to change color.
For example, if you were trying to print a receipt you would need to print letters, numbers, maybe a barcode, etc. To print those things, the paper runs through the printer and as the paper runs across the print head, electrical currents in the print head generate the heat that creates every letter, number, barcode, etc. As the paper keeps moving through the printer the printer prints line-by-line, creating only the currents/heat necessary to create each letter, number, etc.
What are the Advantages of a Thermal Printer?
Thermal printers do not require ink, they can quickly and easily print simple text, and in some cases, they can even print simple images, (like grayscale logos for example). Maintenance on thermal printers tends to be minimal as well. Simply put the right paper in the machine and print to your heart’s desire. The other benefit of not using ink when printing is there is no need to wait for ink to dry. You can have smudge free prints in seconds. All these attributes make thermal printers ideal for printing things like receipts and shipping labels.
What are the Disadvantages of a Thermal Printer?
The largest disadvantage of a thermal printer is that they are more expensive, specifically when compared to inkjet printers. However, if you’re printing with a thermal printer often enough, the upfront cost is easily offset. The low operation cost of thermal label printers is why most retail stores and shipping centers use thermal label printers instead of inkjet printers.
Beyond the upfront cost however, it should also be noted that thermal printers are not made to print much more than text, numbers, and barcodes. Some can print basic graphics, but they typically need to be stark contrast, black and white graphics, (more commonly called grayscale). Most thermal printers only print a single color, and if you’re printing a receipt or a shipping label, that’s all you need it to do. There are thermal printers available capable of printing in two colors, but don’t think of them like inkjet printers which can mix inks to create different shades and variations of colors.
Direct Thermal vs. Thermal Transfer Printers
There are 2 primary types of thermal printers: direct thermal and thermal transfer. Both printers work off the same basic concept of using heat that comes from electrical current/pulses inside the print head of the printer.
In direct thermal printing, the print head of the printer comes into direct contact with whatever material you’re printing onto, (most often specialized paper). The electrical pulses from the print head come into direct contact with the paper, which causes the thermal reaction that makes the paper change color, or what we would refer to as a “print.”
In thermal transfer printing the print head does not come into direct contact with what you are printing onto. Instead, there is a printer ribbon that is in-between the print head and what you want to print onto. In thermal transfer printing the ribbon runs across the print head and the electrical current in the print head causes the material in the ribbon to transfer from the ribbon to whatever you’re printing onto.
You can almost think of direct thermal vs thermal transfer as “direct vs indirect thermal printing”. Direct thermal is a direct contact between the print head and the printed material whereas thermal transfer is more indirect, with a ribbon in-between the print head and the printed material.
See a Thermal Transfer Printer in Action
Thermal Label vs. Thermal Transfer
Sometimes the terms thermal label and thermal transfer can almost be used interchangeably when discussing these types of printers, so we want to clear up any confusion. Thermal label printers almost always tend to be direct thermal printers. They are often called thermal label because they most often print directly onto labels. So, when you see thermal label, you can think of it as direct thermal printing.
Similarly, thermal transfer printers typically do not print directly onto labels and are better suited to more specialized purposes, like printing on heat shrink tubing.
Direct Thermal vs. Thermal Transfer vs. Inkjet Printers
Direct thermal printers are great for printing things like receipts, shipping labels, etc. They do require special paper to work, but so many options exist for printing receipts and shipping labels that this usually isn’t an issue.
Inkjet printers are what most of us have in our homes and workplaces. They are great for printing photos and graphics and anything that requires more color and detail. Inkjet printers can easily become maintenance problems largely because ink can be a tricky thing to work with. It must be replaced often, nozzles need to be cleaned and calibrated, ink cartridges are printer specific, etc. Ink also smudges, which is not ideal for many forms of printing. Inkjet printers can print onto most papers however, and do not require a specialized paper to print, although different types of papers produce different types of print results.
But what if you want to print on something other than paper? That’s where thermal transfer printers come in. For example, we make thermal transfer printers for the purpose of printing onto heat shrink tubing. Direct thermal would not be able to print onto heat shrink at all, and the ink from inkjet printers would easily smudge and not last. Thermal transfer printers solve these problems by having the ribbon transfer onto the heat shrink tubing, (instead of direct thermal), with the ribbon being highly smudge resistant. So, if you’re trying to do something unique, like putting labels onto heat shrink, you’ll want to look at a thermal transfer printer.
It should be noted that thermal transfer printers can’t just transfer their ribbon onto any material. To use heat shrink tubing as an example again, not all heat shrink tubing is made from the same materials. We have designed our thermal transfer printer ribbon with heat shrink tubing in mind but simply cannot guarantee it to work with all heat shrink tubing products and materials out there. For this reason, we have a 3 to 1 (3:1), flattened heat shrink tubing designed for printing that we are able to guarantee the quality of the prints.
The point is that thermal transfer printing is highly specialized. Just like direct thermal is great for receipts and shipping labels, and inkjet printing is great for photos and graphics, so too is thermal transfer great for heat shrink and other highly specialized purposes. Deciding on a printer really depends on your application. If you have a specific application in mind however, especially if the quantity is high, you will more than likely want to go with the printer best suited to your specific application.
Gamma’s Thermal Transfer/Heat Shrink Printers
Here at Gamma Electronics, we focus on thermal transfer printers given how much work we do in the heat shrink tubing world. We offer three types of thermal transfer printers, each of which are capable of printing and cutting different sizes of heat shrink tubing. With our printers you get all the perks of thermal transfer printing. Fast, reliable prints that don’t smudge with far less maintenance than you get with inkjet printers.