Impressions - April 2014 - 61

With LED lamps, screens can be exposed in seconds, making a computer-to-screen UV LED screen
exposure unit the fastest way to expose screens. Photo courtesy of Mind's Eye Graphics, Decatur, Ind.

bulb aging cause spectrum shifts with
LEDs, as it does with other light sources?
Over time, the speciﬁc inert gas and
coatings inside a current incandescent or
ﬂuorescent exposure bulb combine with
the aging of the electrical element to
change the spectrum of the UV light that's
emitted. This typically adds to the amount
of time required to fully expose the screen
so it will wash out and print correctly. (I
deﬁne this as "UV drift;" the tech guys
will throw a ﬁt over this description, but
it works for me.)
For this reason, most current exposure
units incorporate an integrator that measures UV output and adjusts exposure
time to compensate for this UV drift. I

personally have not seen integrators used
with LEDs, and changes in UV output due
to bulb aging may not be an issue.
As I understand it, heat is a primary
factor in UV drift, and in theory, the lack
of heat with LEDs may impact UV spectrum migration to the point where it is not
an issue. No one has had a unit in place
long enough to satisfy my curiosity, but it's
something worth exploring.
If we assume there will be UV drift,
how does one compensate for it? With a
single-point metal-halide light source, one
bulb creates a cone of light that bathes the
entire surface of the screen.
Detail is preserved because all of the
light originates from just one point. With

Changing With The Times
Some members of the decorated apparel industry
are saying LED exposure technology is not all it is promised to be - and in its current state of development,
they may be correct.
However, remember what probably happened at
board of directors meetings at Kodak, Polaroid and
other photo ﬁlm suppliers during the 1990s. Some
bright board member probably brought up the idea of
digital photography for discussion and how it would
be the wave of the future. The discussion then may
have migrated to how it would change individual
business models.
Another sage advisor probably stepped in to remind those in attendance that they were currently
impressionsmag.com

in the ﬁlm business and had billions invested in its
production, marketing and distribution.
In my opinion, what they missed was that they
are really in the memory business and did not even
realize it. The folks at Kodak had even copyrighted
the term "Kodak Moment."
We all know how this story turned out and how
it affected photo equipment and supplies manufacturers. Keep this example in mind as you evaluate
the future of LED exposure in the graphic arts world.
Remember nobody needs another T-shirt; customers
are buying memories that are conveyed via screen
printed garments.
April/May 2014 | Impressions

Use Info*Action #36 at impressionsmag.com/infoaction
See us at ISS Nashville, Booth #711

http://www.VASTEX.COM http://www.impressionsmag.com/infoaction http://www.impressionsmag.com

Impressions - April 2014

Table of Contents for the Digital Edition of Impressions - April 2014