Printing Technology
Thermal Transfer vs. Direct Thermal
Thermal Transfer (TT):
Thermal Transfer printing is when the heat from the printhead is
applied to the ribbon. The material on the ribbon is then transferred
to the label media. As you'll read later, this method is easier
on the printhead, as the back of the ribbon is very smooth and protects
the printhead from the friction of the media. Because TT printing
uses a ribbon, it also opens up other options regarding the type
of ribbon and label media. More information on media is offered
later.
Direct Thermal (DT):
Direct Thermal printing is where the printhead comes in direct contact
with the label media. There's a coating on the label media that
turns black as heat is applied to it. Because of this, no ribbon
is required.
You might be thinking that this would be a less-expensive method
of printing because you don't have to buy ribbons. However, this
method will also wear down the printhead faster than with thermal
transfer. Paper is coarse and will break the printhead down over
time. Also, the edge of each label strikes the printhead, causing
further breakdown. You won't have to buy ribbons, but you'll have
to buy more printheads, which are expensive. The bottom line
is that there is little-to-no difference in the cost of operation
between TT and DT.
Another downside to DT printing is that the labels will turn yellow
over time, and the print will fade to a faint gray. Overnight carriers
typically use DT labels because the labels only need to last a day
or two. It is reasonable to expect a DT label to last about 6 months.
One last thing to remember - heat is what causes the label to
change from white to black. Keep the labels from storefronts, jewelry
cases, and lighting centers.
Dots Per Inch (DPI)
The quality of the print is many times directly related to the density
of the printhead. An image appears on a label due to a single dot
or series of dots being turned on. The greater the number of dots,
the clearer the image.
Printheads come in five different densities: 152 dpi, 203 dpi,
300 dpi, 406 dpi, and 600 dpi. T&W Enterprises will be sure to select
the printer that best suits your business' needs. For example, you
might specify that you need to print "100% UPC." In this case, you
would need a printer with a 152-dpi printhead. A barcode is measured
in mils, which is 1/1000th of an inch. If you need to print 15 mil
barcodes, then the width of the narrowest bar in the barcode would
be 15/1000ths of an inch wide.
If you don't care about printing barcodes, but want to print labels
with pictures, then you'd want to get a printhead with the greatest
density. If you are printing barcodes and don't care about the specific
mil of the barcode, then 203 dpi would probably be your best bet.
Memory
To print an image, the printer must store a portion, or all, of
that label image in its memory before it prints the label. There
are different types of memory that serve different purposes.
SRAM / DRAM:
A printhead may be the proper density to print a picture on a label,
but the printer may not be able to store that entire image up in
memory. This is where SRAM or DRAM comes into play. This gives the
printer the ability to allow the printer to print a longer label,
as well as store that large image in memory. Any data stored in
SRAM or DRAM will be lost when the power to the printer is turned
off.
Flash:
"Flash is like a floppy." If the printer has to wait for the host
to send an entire image down every time it wants to print it, the
printing is going to be very slow. Having Flash memory will allow
you to store the image on the printer, which will greatly speed
up the printing of the label. It's like a floppy diskette because
it is permanent storage and does not require power for the data
to be maintained. In some cases, it is also portable.
Media Matching
Labels and ribbons come in different varieties. Labels can be paper,
polyester, polyolefin, or polypropylene, to name just a few. Ribbons
can be wax, a mix of wax and resin, or resin.
Interfaces
Serial:
A printer with a serial port will almost always connect to the
serial port of a PC. Serial ports on a PC are always male, and have
9 or 25 pins. Though the pinouts of the serial port on a PC are
always the same, the pinouts for the serial port on a printer are
not always predictable. Many times, a "null modem" cable is all
that's needed, but other solutions may be required.
Parallel:
The parallel port on a PC is always 25-pin female. Again, most printers
with a parallel port will have a Centronics interface, but may require
other interfaces. T&W Enterprises has the peripherals that plug
into the Centronics parallel port on the printer and convert the
parallel ports to Ethernet or USB.
Universal Serial Bus (USB):
This is new, but much needed technology. USB is faster than serial
or standard parallel communications (ECP/EPP parallel is faster
than USB), allows you to connect up to 127 devices to a single PC,
and can go as far as 82 feet away from the PC. Serial is limited
to about 50 feet and parallel to about 15 feet.
Ethernet:
"10Base-T" and "10Base-2" are terms that you'll hear associated
with Ethernet. 10Base-T uses phone jack (RJ) connections, while
10Base-2 uses coaxial (like your cable television cable) connections.
Having an Ethernet port on the printer will allow you to connect
the printer directly to your network, thus negating the need for
a PC to function as a print server.
Twinax:
A Twinax (5250 emulation) interface is required for connecting a
printer directly to an IBM AS/400 or IBM 3x System.
Coax:
A coax (3270 emulation) interface is required for connecting a printer
directly to an IBM mainframe system.
Software
Regardless of the manufacturer, every thermal printer manufacturer
has a proprietary printer language that they use for their printers.
In some cases, the manufacturer has some printers that use one language
and some printers that use a different language. Programming guides
for these printers are generally available.
There is software available that will enable you to design and
print a label to a long list of printers from different manufacturers
using a graphical user interface.
Finally, how many inches of labels a day would you like to print?
Printer manufacturers make printers for different applications.
Just like you wouldn't take your Honda Civic out to pick up a load
of mulch or firewood, we wouldn't recommend a printer designed to
create labels for a small boutique when you need a printer for a
warehouse that will be printing 20,000 inches of labels every day.
This also works hand-in-hand with print speed. If your business
needs to print 20,000 inches of labels every day, you are probably
going to want a printer that can print faster than 2 inches per
second.
Selecting the proper printer ultimately comes down to T&W Enterprises
understanding your business application. For assistance in selecting
the right printer for your business contact T&W
Enterprises Technical Support.
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