n
These displays come in 1.44”, 2.0”, 2.7”, 3.0”,
4.41”, 7.4” and 10.2” sizes. The technology was
of course developed for eBooks but can be
used in any application where power con-
sumption is a major issue, as the displays only
draw a small amount of power when they re-
fresh and can retain content indefinitely with-
out any power. They are also designed to be
used in sunlight-readable conditions and with
a very wide viewing angle. The display can
therefore form the integral part of a solution
for shelf labelling, digital signage, security and
luggage tags, energy meters, conference room
notice boards, hotel notice boards and museum
information boards, to name just a few of the
many and varied applications that Densitron
and its partners are working on. PDI has part-
nered with E Ink, the industry leader in e-
paper film, to produce so-named electrophoret-
ic displays that are bistable in nature - they re-
quire no power to maintain an image on the
screen. An electrophoretic display forms visible
images by rearranging charged pigment parti-
cles using an applied electric field.
PDI assembles e-paper modules by adding the
E Ink film on top of a Chilin active-matrix
TFT backplane and then covering it with a
protective sheet. This TFT backplane enables
the E Ink film to be divided into pixels, and
controlled to form a desired image. The panel
is driven by chip on glass ICs and timing con-
trol software, which is stored and executed on
a microcontroller on an attached printed circuit
board (TCON). The timing control software
is one of the most crucial parts of the system,
creating complex waveforms to ensure good
image quality. Good image quality is ensured
by moving the charged particles to exact loca-
tions in order to display a white or black pixel.
Temperature sensing is also employed on the
TCON to negate the effects that temperature
has on the viscosity of the fluid inside the mi-
crocapsules. When the fluid becomes more
viscous at lower temperatures, the pigment
chips move more slowly and this requires a
different waveform to obtain the desired image.
Many TCON options are available to provide
USB, Serial, or wireless interfaces to e-paper
modules, and also extension boards that pro-
vide interfaces to the most popular microcon-
troller development kits.
The eye catcher picture shows a bus timetable
application developed by Densitron for IBI
Group working on behalf of Centro (the West
Midlands Passenger Transport Executive and
Authority). Centro along with most transport
providers/operators have a requirement to pro-
vide up-to-date and accurate timetable infor-
mation on street. The system developed by
IBI Group integrates with the Centro timetable
and real-time information system to provide
this information on the display unit, which
consists of eight 10.2” e-paper displays, all of
which is done from a central control centre
via GPRS communications. The system went
live in June in the Oldbury area of the West
Midlands.
Future plans for the system include integration
of disruption and diversion information, road-
work information, integration with other modes
of transport, i.e. trains and light rail, and addi-
tionally the system could be used to get infor-
mation to the general public quickly. For ex-
ample if a child goes missing then a picture of
the child can be distributed to the displays im-
mediately asking for assistance from the public.
Densitron building on its experience of low
power timing control modules is also creating
a family of products that connects the displays
to the internet. The first of this new range of
products will be a POE (power over ethernet)
solution that allows any number of e-paper
displays to be tiled to create a large digital sign.
Current display sizes supported are 4.41”, 7.4”
and 10.2” which can be tiled to create a display
to any size required with any number of displays
incorporated. A simple backend system will
allow the distribution of information over all
the displays in the system.
The latest development is the creation of a
Densipaper subsidiary providing WiFi-based
E-Paper display solutions. This solution will
E-paper displays suited for a
multitude of applications
D
ISPLAYS
By Grahame Falconer,
Densitron
Everyone is familiar with
e-paper displays in Kindles
and Kobo devices. However
e-paper displays are suited for
integration in many industrial,
business and commercial
applications. Densitron has
the sole rights to market
the e-paper range of displays
in the UK from Pervasive
Displays Incorporated(PDI),
part of the Chi Lin Taiwan
Display organisation.
April 2014
36
Figure 1. Centro’s timetable and real-time
information system to provide this
information on the display unit which
consists of eight 10.2” E-Paper displays
