Thermal barcode printer resolution

Thermal and thermal transfer printers use a printhead made up of individual dots that heat up to melt ribbon onto a label (thermal transfer) or darken some heat sensitive media (direct thermal). In either case you’ll need to determine the best printhead resolution for your application.

Printhead resolutions are specified in dots per inch, (dpi) and are nominally 200, 300, 400, or 600 dpi. The individual dot size for these are 5 mil (.005 inch), 3.3 mil, 2.5 mil, and 1.6 mil. Of course, a printer can’t print anything smaller than its dot size. Printheads are usually 4 inches wide, but you can also get them in 2, 6, and 8 inch widths.

Which resolution should you use? That depends on what you are printing.

If you’re printing shipping labels for UPS or Fed Ex and all you need is a legible address and bar codes that the shipping companies can scan, 200 dpi is the choice. Replacement printheads are cheaper and print speeds are higher at 200 dpi.

A few years ago the only way to print more data into a bar code in a small space was to print narrower bars. Not many applications used narrow bars (called the X dimension of a code) smaller than 5 mils. Today you would use a 2D code like Datamatrix to fit more data in a small space, making printhead resolution less important when printing small labels.

The real reason to use a higher resolution printhead is when you need to print a logo or small text; marketing people are very fussy about logos and the look of their finished goods labels. Here’s the same logo printed at 200 and 400 dpi. You’ll see that the 200 dpi suffers from jagged edges when printing curves or angled lines.

The effect of resolution is a lot more apparent when printing small images and text. Labels in the medical industry often require small images and warnings or instructions in multiple languages. It’s common to prepare these in Photoshop and save them as a bit map image to avoid the complexity of printing multiple languages on the thermal printer. Here are two examples, again at 200 and 400 dpi:

This image is blown up slightly, but the 200 dpi printing is unacceptable, the 400 is legible.

 

 

Why you should only use printers with displays

The Honeywell PM and PC series of printers are available with color displays. You can also order these without displays to save some money and use the LEDs/icons instead.

We don’t sell these printers without displays. The display gives you immediate access to the configuration menus, wizards, and error messages that make support work far easier.  Here’s a display and icon printer that have run out of labels:

Notice that there is a Wizard button under the message on the display unit. Pressing this will show a user how to install labels in a series of step by step pictures.

Printers are normally assigned a static IP address, or a reserved IP address via DHCP. But, when you first connect a printer to the network, how do you know the IP address that it has been assigned? This is easy with a display, it can be shown on screen. With an icon printer you have to first set up the media type, then calibrate the printer, wait two minutes and press and hold the feed key for three seconds. Test labels will print that show the current IP address of the printer, as long as the labels are the correct size and the IP doesn’t print off the side of the label or on the gap in between labels. Or you can make a static ARP entry using the printer’s MAC address on your PC, browse to the printer and set up a static IP, but that’s beyond most users.

There are some features that are only available with printers with displays. One of my favorites is the print quality wizard. The two things that determine the print quality of thermal printers are speed and heat. In general, slower printing yields better quality, and the heat applied by the printhead needs to be matched to the speed and materials used. There are three types of ribbons (wax, wax/resin, resin) and many types of label materials. Getting the right settings can be challenging.
The print quality wizard first asks you for the print speed (go slow!) and then prints five different labels using different media sensitivity settings. It then asks you to pick the best of the five and then prints three more labels at different darkness setting and again asks you to pick the best one. This is usually sufficient to dial in the settings properly, but you can manually change the print contrast for additional control, if needed.

These printer are also programmable, and having a display makes software a whole lot more user friendly.

If you are worried about user’s getting into the menu system and messing up your settings you can control access to the menu system through the menu system or the printer’s; web interface:

PC series printer web interface

You can disable access to the menu system, or enable it with a required PIN number to log in.

The difference in price between a PC43 with a display and one without is less than $69, well worth it. The same advice applies to the PM43 series.

One more tip on buying a PC43 printer: if you want a LAN connection for your printer, order it separately and install it yourself. If you order a PC43 with Ethernet already installed it is $131.20 (at our discounted price) more expensive, and the adapter ordered separately is $104. Installation of the adapter is very easy. All you need is a small Philips screwdriver and it won’t take more than a couple of minutes to install.