LED Printers: The Quiet Achievers You May Not Have Heard Of - Ibbit
[https://hackaday.com/wp-content/uploads/2018/04/incandescent.jpg?w=800] Many
different types of printers have entered the market over the years. Most of us
are intimately familiar with the common inkjet and laser, both of which can be
found in homes and offices all over the world. Then there are those old dot
matrix printers that were so noisy in use, thermal printers, and even solid ink
printers that occupied a weird niche for a time. However, very little attention
is ever paid to the LED printer. They’re not actually that uncommon, and they
work in a very familiar way. It’s just that because these printers are so
similar to an existing technology, they largely escaped any real notability in
the marketplace. Let’s explore the inner workings of the printer tech that the
world forgot. ## Blinding Lights To understand the LED printer, it helps to
first understand the laser printer, and before that, the photocopier. Indeed, it
was the latter technology that spawned the xerographic process that underpins
all three machines. Xerography is a compound word, from the Greek words xeros
(dry) and graphia (writing). It’s where the Xerox company earned its name, and
the process is at the heart of the photocopier. In the modern form we’re all
familiar with, a photocopier relies on the use of a cylindrical drum, coated in
a photoconductive material. This drum can be given an electrostatic charge,
which remains on the surface when in darkness, but is conducted away when
exposed to light. In a photocopier, the drum is exposed to light from a scanning
lamp passing over a document. Where the document has light sections, the charges
on the drum are conducted away, and where there are dark sections, the charge
remains. The drum is then exposed to tiny particles of toner, which are
attracted to the charged areas on the drum. A corona wire is then used to
generate an opposite charge to that of the toner, pulling it off the drum and
onto a piece of paper to replicate the original document. It’s then merely a
matter of heating the paper to fuse the toner in place by melting it, and then
the completed document is fed out of the photocopier. It’s this final step that
gives fresh photocopies their characteristic warm feel and mild plasticky smell.
[https://hackaday.com/wp-content/uploads/2026/02/Laser_printer-Writing.svg_.png?w=400]https://hackaday.com/wp-content/uploads/2026/02/Laser_printer-Writing.svg_.png
Laser printers use a scanning laser to discharge a photosensitive drum, which
then picks up toner and deposits it on paper. Credit: Dale Mahalko
[https://en.wikipedia.org/wiki/File:Laser_printer-Writing.svg#/media/File:Laser_printer-Writing.svg],
CC BY 3.0 It wasn’t long before the xerography process was applied beyond mere
photocopies. Xerox engineer Gary Starkweather realized in 1969 that a scanning
laser beam could be used to draw directly on to the drum in place of the
scanning lamp of a photocopier. A few years later, this led to the development
of a prototype which proved the concept, and by 1976, the first commercial laser
printer was on the market. These printers were prized for their high speed and
initially used in data center roles, before smaller desktop-sized units reached
the market in the 1980s. Laser printers vary in construction, but most use a
single laser diode with a rotating mirror that scans the beam over the drum. The
beam is modulated as the mirror scans and the drum rotates to only remove
charges from the drum in light areas that are not to have toner deposited. For
color printing, some laser printers implement multiple drums, one for each color
of toner—cyan, magenta, yellow, and key (black)—with four scanning lasers
required in turn. The paper is passed over each, picking up one layer of toner
at a time before it’s fused into the paper to create the final image. Some
printers have also added a “transfer belt” to ease registration issues in color
printers, wherein the drums deliver each color of toner to a belt, and the belt
then delivers the toner to the paper in one fell swoop.
[https://hackaday.com/wp-content/uploads/2026/02/Laser_unit_dell_p1500_print.jpg?w=400]https://hackaday.com/wp-content/uploads/2026/02/Laser_unit_dell_p1500_print.jpg
A scanning laser unit from a Dell P1500 laser printer. Note hte hexagonal mirror
and the lensing assemblies to focus it on the drum. Credit: Jeroen74
[https://en.wikipedia.org/wiki/File:Laser_unit_dell_p1500_print.jpg#/media/File:Laser_unit_dell_p1500_print.jpg],
CC BY-SA 3.0 Laser printers are capable, high-speed printing machines, but they
are expensive and do have a lot of moving parts. Engineers at Oki eventually
realized it was possible to replace the combined laser diode and spinning mirror
assembly with something simpler and more solid-state. Thus was born the LED
printer, first developed in 1981 and commercialized in 1986. Rather than
scanning a laser beam across a cylindrical drum, the LED printer has a line
array of tiny individual LEDs that remove charges from the drum instead. The
printer otherwise works in pretty much exactly the same way—only the method of
discharging the drum was changed.
[https://hackaday.com/wp-content/uploads/2026/02/Screenshot-2026-02-26-132022.png?w=400]https://hackaday.com/wp-content/uploads/2026/02/Screenshot-2026-02-26-132022.png
A diagram of an LED printer head for discharging a photosensitive print drum.
Credit: Oki
[https://www.oki.com/global/technologies/otr/assets_c/uploads/otr-222-R08.pdf]
LED printers are generally a bit cheaper to manufacture, and can sometimes print
faster than comparable laser printers. In part, this is because the line array
can flash a segment of the drum all at once versus a laser beam which must be
scanned across it. Where laser printers routinely offer 1200 x 2400 DPI
resolution, it took LED printers some time to reach the same heights, as fitting
1200 LEDs into a single inch is no mean feat. However, Oki was able to achieve
this milestone by 1997, while some cheaper models sit at the 600 DPI level
instead. Meanwhile, in 2024, Canon did produce a LED-type printer using OLED
technology, which enabled resolutions up to 4800 x 2400 DPI. The higher light
emitter density possible with OLED technology allowed this leap forward.
Notably, most color LED printers tend to use a transfer belt setup, in which
each LED/drum unit delivers toner to the belt which is then deposited on the
paper in one pass. This is why LED printers tend to have similar print speeds
for color and black-an-white use. This was an advantage over older color laser
printers that didn’t use transfer belts, but instead had a color page make four
separate passes over a drum, slowing printing down significantly. Canon
leveraged OLED technology to produce an LED-type printer with far superior
resolution to traditional designs.
[https://hackaday.com/wp-content/uploads/2026/02/Screenshot-2026-02-26-133402.png?w=400]https://hackaday.com/wp-content/uploads/2026/02/Screenshot-2026-02-26-133402.png
LED printers are commonly marketed with “laser” in the copy because consumers
don’t know what an LED printer is. Credit: Screenshot, Brother website Funnily
enough, some LED printers fly under the radar and are sold as “laser printers”
despite not containing a laser. This is because, to the end user, the technology
is not particularly different—the printers still use a charged drum for printing
and still use toner to make an image. LED printers never differentiated
themselves enough to make a big splash with disinterested consumers and
commercial buyers who just want well-printed documents at the end of the day.
LED printers mostly just look like laser printers and work similarly enough that
few ever noticed the difference. Often, an LED printer will show up on
e-commerce sites with “laser” scattered around the marketing copy because many
understand them to be essentially the same thing from a user perspective. LED
printers are unlikely to become a household name any time soon, even if you have
one in your household—if only because their close association with laser
printing technology means most people never noticed they existed in the first
place. In any case, next time you’re sitting at a table at your friend’s wedding
with a bunch of people you’ve never met before, you now have an incredibly
tedious technical lecture you can deliver to impress everybody at dinner. Spread
the word about LED printers, because they’ve failed to do it themselves! — From
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