ECRM autokon 8400
author ralph klimek 2008
the ECRM autokon 8400 (740) was an electronic device designed to reduce
pre-press camera room production costs. It was a machine for
electronically screening contone pictures and outputting halftones that
were ready for compositing with a process camera. The machine was
designed in the late seventies and used commercially into the early
ECRM Autokon laser scanner/camera was a remarkable and ambititous
device that used an extraordinarily complex hybrid analog computer,
complex hard wired digital logic functions, a large optical bench and
up to two helium-neon gas lasers to scan continuous tone monochrome
photographs and directly write to bromide the half tone screened image.
I learned to service these troublesome devices whilst working at
Xenotrons' Melbourne HQ in 1983. This article is an attempt to lay some
ghosts, this machine was one of the banes of my life at this time and
the overwhelming support work load thus engendered, caused me to look
for greener pastures. The machine contained many concepts that were new
and unique and many examples of how not to do things. There seems to be
absolutely no reference to this machine on the world wide web apart
from mention in assorted operators resumes, even the parent company,
ECRM, now fails to mention them much. They were a revolutionary machine
for the time. They heralded great and profound changes occuring in the
Purpose of the Autokon.
traditional printing press is a "digital" device , it can either
desposit a dot of ink, or not deposist a dot of ink. If it be
monochrome, then that dot is black...and nothing else. A press cannot
print even one tone of grey, let alone the thousands of grey levels
that come with a monochrome continuous tone photograph. A means must be
found to translate grey levels into discrete dots of ink, whereby the
relative size of the dot represents a grey level of the original
image. This is traditionally done in a large process camera, the
original image is overlayed with a screen ruled at a resolution that is
just printable by the printing process used by the publisher. So for
example, cheap letterpress newsprint, the screen would be 55 lines per
inch, and good offset lithographic printers, could use a screen of 100
lines per inch or better. The process camera takes , on high contrast
high gain medium an image through this screen. If the gray level just
visible through the grid is greater than the bromides' theshold, it is
registered as a black picture element, if not it is considered white.
The traditional process is expensive in materials, time and labor. The
process camera operator was skilled in dark room techniques, it was a
skilled trade and jealously protected by the craft unions. A good
camera operator could do basic image enhancements like shift the
contrast and brightness levels from a badly exposed original up to the
press requirements. A truly skilled camera man could do unsharp masking
to improve the subjective image resulution, but Im sure given the
pernickety requirements, was only done by Intelligence organizations
attempting to recover the maximum millitary value of impossible to
obtain images. The pre press camera room would also require a library
of screens for differant presses and processes, including novelty
screens for quality magazines and books. These screens were hideously
expensive , being created by special ruling engines. As I recall in
1983, these was supposedly only one producer of screens left on the
planet and they charged like they meant it!
Description of the Autokon.
was a large free standing machine, that had many internal improvements
over the life of the product, but the basic shape and frame remained
unchanged. There was a flat vacuum conveyor belt that held the
original, moveable guides that performed the cropping function, a
cryptic control panel of two parts, the normal operator controls and
behind a door, the so called advanced controls. The conveyor brought
the image into the scan station where two differant laser beams scanned
the image, and as it scanned it wrote the "screened" image directly to
bromide which would be discharged into a light proof canister. The
original would be discharged at the end of the conveyor, if it had not
snagged on the machine internals, thus requiring a field service call
to remove it. The operator could set the input white and saturated
black level on the machines front panel, the readin being derived from
a densitometer, or by shear dumb luck. The midtone setting was done by
guesswork, the effect of the control was to adjust the gamma of the net
optical transfer function. In "lineart" mode the midtone setting
changed the black/white decision threshold level. The operator selected
the screen to be used and fiddled with controls to achieve artistic
effects, provided that they understood the machine sufficiently. In my
experience the operators never used the special features, they were not
reproducible enough to form a work flow process around. In general they
were just gratefull to get an image out of it before the machine broke!
The machine was really intended to take the guesswork and black art of
the camera room and render it into a "just push the button" semi
skilled process, which naturally appealed to large newspaper
publishers. There was some saving in materials, as the Autokon
machine generally had reproducible results, only one run was generally
required to get a good screened image, compared with multiple runs on
the process camera from which the "best" would be selected. The Autokon
could also do anamorphic imaging, and this was heavily used by
newspaper pre press, particularly be the advertiseing copy people that
needed to make advertiseing artwork and type from external agencies who
did not understand the newspapers format requirements, fit into the the
newspapers column format. This was something that the traditional
process camera could not do.
Internal mechanism of the Autokon.
design of the Autokon was brilliant, the implementation was mixture of
ham fisted idiocy and technical excellence . The outcome was a machine
of unwarranted complexity and limited reliability that was quickly
replaced in the marketplace when cheap flat bed scanners became readily
available. The single line self scan CCD array chips ended the Autokons
use and market for input scanners.
The optical bench.
large half inch thick aluminum plate held all the optics. Coherent
light from two laser sources were directed and manipulated to create up
to four seperate beams. One beam was directed to the scan station where
it would scan the input image in one axis as it was being moved by the
conveyor belt. Another beam was directed to an optical grating bar that
would provide an internal beam position and reference clock . Another
beam was created for writing to the recording film . One extra beam was
created that was also directed to the scan station. This beam was
defocused with respect to the other reading beam and also modulated at
about 10Mhz. The combined video signal was processed to seperate the DC
component the the modulated component. The two signals were processed
at video speed in an analog computer to perform the level shifting
functions and to perform unsharp masking at the same time. This
part was absolutely remarkable. The Autokon was famous for
producing (when it worked!) crisp detailed halftones with "clarity"
that sports editors loved. In the original design two gas laser
tubes and there was a troublesome servo using the acousto-optic
modulator to modulate the intensity of one of the lasers. This caused
so much trouble, especially as laser tubes did not age in the same way,
that design was abandoned and one laser with a beam splitter to
derive the second laser source on the same optical bench was then used.
When I took over Autokon maintenance in Australia I insisted that all
Autokon had to be retrofitted with the single laser option. I was very
glad for this change, it significantly reduced service calls. It seemed
bizarre to me why two lasers had to be used given the extraordinary
difficulty in getting two gas lasers to track each others' intensity.
The scanning beam was deflected not by a spinning prism, as was done in
laser typesetters and laser printers, but by a galvanometer motor,
which was cheaper and required simpler optics.
station optical pickup was truly remarkable. Two offset ellipsoidal
mirrors ran across the scan. The focal plane was lined with silicon
photo voltaic diodes, the other focal plane was positioned so that the
input image plane coincidended with it. The laser dot line scattering
off the input image would be nicely focused onto the photodiode line.
The film output was driven by a belt driven
synchronous motor that ran at a fixed (mains) fequency. Anamorphic
reproduction was achieved in one axis by changing the speed of the
vacuum conveyor belt. A turret holding tiny mirrors deflected the
four beams onto the galvanometer scanning mirror, all beams were
directed through a field flattening lens that maintained tight focus
over the scan plane.
The mirrors and beam splitters used
silvered uncoated mirrors on aluminum mounting posts. This was the
undoing of the machine. How long do you think uncoated silver stands up
to the fumes in a camera room ? The Autokon was invariably placed inside
damp, humid, dusty ,dark camera rooms and how long do you think silver
mirrors lasted ? Not very long. In a few months the silver
coating would simply flake off the mirrors and along I would come to
perform a complete optical alignment and mirror replacement. The
aluminum posts did not help, they deflected, aged badly and adjustment
threads would be stripped in no time. Later Autokons had steel posts. I
dont know if coated mirrors were ever used, I did not stay around long
enough to find out. In order to have the machine manufactureable,
alignment posts and points were provided on the bench, and this was a
very good part of the optical design, it could be completely aligned
out in the field. I used to carry a small piece of polaroid film around
with me, that way I could knock the laser intensity down to a level
such that I could bear to look at the alignment targets. The laser
tubes were nominally rated at 20milliwatts output and the machine was
serviceable down to about 5 milliwatts. I spent a lot of time replacing
An acousto-optic modulator is a device for
modulating gas lasers which cannot be modulated eletrically. It is a
piezo electric device whereby a acoustic standing wave is created in
the crystal (lithium niobate) by ahigh power radio frequency signal.
This sets up regular density
waves in the cystal that has the same
effect on coherent light as would a diffration grating. The AOM is in
effect a programmable differation grating. The first order diffracted
beam was the one that was used. This meant that 80 % of the laser power
was thrown away, that was too bad, the need to modulate it was what was
important. The efficiency of the process could be vagualey controlled
by the power of the radio frequency energising source, and it was
through the AOM that the heroic attempt to make two gas lasers
intensity track each each was acheived. The method was never
truly successfull, so ultimately, only one laser was used.
Video signal processing.
signal picked up by the scan station photo diodes was amplifield in a
circuit that went through many iterations. The amplified siganl went to
the analog board. The sharp beam signal was seperated from the unsharp
beam signal. The unsharp signal went through bandpass amplifiers and a
synchronous detector to recover the actual video signal. A
amplitude differance signal was produced between the sharp and unsharp
video. A variable amount of the differance signal could be added
to the final output video signal. This had the effect of enhancing the
edges of images and improved edge contrast. Programmable amplifiers set
the gain and offset of the video. A sub feed of the video went to a
network of analog multipliers and high speed op amps that performed the
midtone manipulation and the effect was to perform a variable gamma
operation whereby the mid point of the optical transfer function could
be shifted in shape, within the bounds set by the highlight/shadows
endpoint controls. This analog computer had a long and torterous
adjustment procedure with many interacting pots. You never really knew,
at the end, if you had done it right. The most galling aspect to this
procdure was that the analog board was supported only on its edge
connectors which carried millivolt level analog signals. The adjustment
was sensitive to flexture in the edge connectors. This was absolutely
revolting as the ajustment had to be carrier out on an extender board.
The analog board also contained the bit slicer, a high speed comparator
that compared the instantaneous video level level with the output of
the "screen" rom to determine if a pixel element was to be set on the
The dot board.
dot board was what actaully performed the "screening" function. The
screen roms contained an image of an actual screen. They were addressed
by a counter whose clock source was derived from a phase locked loop
whose reference clock was the signal coming from a phtodiode strip
behind an optical grating that was scanned by one of the four beams.
Another phase locked loop was driven by the conveyor belt motors
optical shaft encoder. This also fed another counter. Here we had two
counters, whose count was a function of instantaneous beam position and
conveyor belt position, these addressed the screen rom whoose outputs
fed a high speed DAC. The output of the DAC could be shifted in gain
and offset ( the bane of Autokon engineers) and the output compared
with that comparator in the video board. Here was the mechanism that
converted the continous tone input video into the half tone signal
which then on/off modulated the recording laser across the bromide as
it scanned and moved in the vertical axis. The dot board was a digital
nightmare, there was no clear design. It had clearly evolved from
kludge upon kludge and I recall being told that nobody really
understood it, the design worked and while it worked they would
continue to manufacture it! These days we would use an FPGA or high
speed DSP or even a network of PALs. This was all asynchronous random
logic WITH feedback. Foretuneately none of these horrible circuits
died under my watch, just as well.
entire machine was controlled by a network of 555 timers, most likely
designed by MIT vacation student engineers. In an era when
microprocessors were around ( think 6800, 8080 et al ) boards covered
with trimpots, 555s and random logic sequenced all functions of this
machine. Setup was an immensely frustrating affairs of trial and error
as we wrestled with inumerable trimpots to make the machine behave
correctly. The controller boards were not interchangeable without going
through the tuneup procedure. One of the most objectionable features
were the cropping arms. The design and intention was good. The cropping
cursors were attached to 10 turn servo potentionmenters, the output
gained and offsetted to internal meaningfulness. An ADC converted the x
axis to digital values that were compared with the x axis counters.
This would define the "cropping" by enabling the print beam inside the
crop area. The y axis crop was set by comparators that determined when
the conveyor leading edge reached the scan station and when it left.
This settup could take a day or trial and error, most times it was
about right. After all, cropping could be done with a Stanley
Knife ("box cutter") far more effectively !
function was not done with a hundred bytes of assembly language
and a 6800 or 8080/Z80 was unforgivable. I think the last model
the 1000 series, ECRM saw the light and used microprocessors for the
first time and biult a good and serviceable product, but it was too
late for me.
Other features and boards.
were a few other boards about the machine, the laser control board ran
the AOM and supplied the 80Mhz VHF amplifier to drive the AOM.It had
the 10Mhz video signal carrier osciallator that was mixed with the VHF
signal. The VHF amplifier power level could be shifted to provide a
primative film exposure control ( and was used for laser tracking in
older dual laser machines)
there was the strange autocal board. One of the problems with the
scan station photodiode sensor strip was that it used photo voltaic
silicon photo diodes. These were not very sensitive at the red He-Ne
laser light frequency, and their sensitivity is not constant between
diode modules and even not constant over the active area of the
sensor. This would require carefully matching of photo-diode
units in production. At worst it could lead to a vertical banding in
the output image. That was not all. The camera operators would take
output from the compositors that used hot wax to cut and paste there
images down to board. Over time, vapours from the wax would condense on
the cold elliptical mirror surfaces and this would result in banding on
the output image. The autocal board would be primed with an alternating
carboard pattern of saturated white and saturated black, the density
being read of a densitometer, the black and white endpoint controls
set. The machine would read in the the chart and then fill a RAM with
gain and offset control data that would be dynamically applied to the
recovered video signal. When the autocal board worked it could
automatically compensate for most of the machines self induced drift.
As I recall, autocal failures were incredibly diffcult to debug.
was an optional screens board, containing a bank of ROMS containing
optional screens, including standard ruled screens and a large variety
of artistic screens, inlcuding the fascinating greek maze and the
remarkable mezotint screen. The art of the mezotint, was commented on
by the great M.C. Escher as being impossibly difficult to accomplish by
traditional methods, yet the Autokon (when it worked!) could do a
mezotint like the masters.
The online market had not been
overlooked, there was the much cursed Formatter Board. It was a unique
and irreproducible hi speed buffered parallel interface much cursed by
interface designer engineers at Xenotron and Monotype . I saw an
interface board designed by Linotype for their system, it plugged
directly into the Autokons backplane and utilized the raw timing and
analog signals. The Autokon could be used as an online scanner, and
could deliver to a host system raw contone data, or screened halftone
data. ECRM had recognised the online market and also marketed a
cutdown version of the Autokon without some of the output recording
components as the model 8200 (later the 720)
I had to support a
small number of these monsters. They were effectively unsupportable in
the field. It invariably become a finger pointing squabble with the
host computers vendor as to which one was busted. Without any kind of
stand alone visualization tool, all we could do was examine various
test points for known waveforms and see that the online signals going
to the host were wiggling up and down in a sensible way. Funnily
enough, the faults that I encountered were mostly the fault of assorted
stand alone interface boxes, full of random logic and microprocessors
that attempted to take the prosiac formatter board ouput and turn it
into something that third party systems could understand, like GPIB. (
GPIB was to controllers and minicomputer what USB is today ). I seem to
recall that the formatter board interface was bi-directional, the host
system could write and image to the Autokon for output, but I never saw
anybody use this feature, which was a pity because it would have been a very capable output engine for a RIP.
There were many things that
were right with this machine, and many things that were wrong.
Servicing this machine was a profound and valuable lesson in electronic
engineering and physics that I dont regret , allthough I am still cross
that the bad engineering I encountered all but destroyed my private
life, Australia wide service demanded an 18 hour day, twenty four seven
with an inhuman amount of travel.
Here is my litany of complaints and gripes.
The Autokons optical bench used elemental Silver surface mirrors,
uncoated, which meant that they were heavily exposed to fumes in camera
rooms, the same fumes that dissolve Silver.
materials. The mirrors were mounted on posts made from aluminium.
The alloy used was subject to aging and worse, the ajustment threads
were too easily stripped. Later models used steel posts.
Optical adjustments were done with screws that used a hex key head. No
qualms about that, except that the key size was non standard. The
standard hex or Allen key available here simply did not fit. I have
seen similar hex head screws in other optical equipment. I still
have in my tool box a momento I still treasure. It is a set of official
ECRM hex keys, they have saved my bacon often. I still cannot source
these particular size keys anywhere. A number of long distance
service call were thwarted by the lack of the right size key.
Lack of a proper card cage.
This design fault/oversight is unforgivable. The circuit boards
were large and heavy. They stood upright in their edge connectors,
totally without any other mechanical support. They wobbled. This was
awfull because there were analog control and data signals on that
backplace for which millivolt changes were significant. It was
infuriating to watch on the scope, your carefully adjustments rendered
void because the card had wobbled. This would result in many
intermittent failures that some customer's local engineers resolved in
crazy ways. I inherited one service account, the main complaint
being the intermittent nature of the machine. On examination, the video
baords edge connectors had been literally eroded away by the site
engineer with emery cloth. Every time the machine failed, he removed
the video board and rubbed a little more of the edge connector away!
The cage containing the boards had unfiltered air blown at them. The
cage quickly filled up with paper dust, and if the Autokon had been
placed in the camera room, filled up with damp corrosive paper dust!
designers had thoughtfully included a power point for the service
engineering to plug a CRO into, sadly this used the american standard
outlet, so I was allways looking for a power outlet at the customers
site and these could be hard to find. I could not source a plug for the
inbiult outlet. In any case, it was useless as the machine had been
biult to american power standards, 115 volts. Export models had a big
step down transformer. Early examples even included an inverter that
converted manins power 50Hz to 60Hz ! I cannot imagine what they were
The power transformers ,in the collection
of linear power supplies, did not have a magnetic shield. This was bad
news as they induced hum into the low level video signal and control wires.
Ridiculous user controls.
The calibration procedure for machine without the autocal option
required the operator to jab a screw driver into a pair of trimpots on
the video board. I had to replace a number of stabbed trimpots. Why
were these not proper control pots ? Some "user" controls required the
operator to open the card cage and fiddle with internal switches.
Sometimes, the camera operators' fingers would drip with developer
solution, right into the electronics. Yuk. There was another control
panel, behind a cover, hiding the "advanced controls". These could
apply an number of badly thought out artistic effects. Also hidden here
were the anamorphic control thumbwheels. I lot of servicecalls simply
required me to return all the myriad controls to their default settings
! After crossing Australia, this could put me into less than a
satisfactory customer facing mood!
Lack of microprocessor control.
The entire machine was sequenced with a network of 555 timers, all set
with trimpots. This resulted in ridiculous control logic of
unimaginable complexity and irreproducible behaviour. It was
mostly undebuggable but yet I, somehow, fixed many.
An ocean of trimpots.
If the designers could not calculate some circuit parameter they put a
trimpot there. Some of those wretched pots were an never ending source
of intermittent faults and drift.
Two lasers where a single laser was sufficient.
was nearly impossible to get two machines to produce similar output. It
was actually impossible to get three machines to perform the
same! Most sites only had one machine, no big deal. Three
machines required a full time support effort. The main problem was
setting the so called end dots. One of the requirements of
printing half tones is that an area of full black results in smudging,
and an area of pure white was unprintable. A minimum number of dots had
to remain in either area. This amount was subject to the whim of the
printer operators. This setting required a tedious setup with the CRO
whilst trying to watch a dancing signal, then set gain and offset. The
controls interacted, it was not possible to set them independently. My
last and final customer had three Autokons! At this point I came to the
conclusion that there were easier and less frustrating ways of earning
a living . By way of consolation ( if I wasnt in tears at this point, I
must have looked it !) the customer gave me a trophy which I still
treasure. It was a metal printing plate of The Australian which still
adorns my office.
Absolutely unforgivable. Attenuators in the print beam were not fixed
in place but allowed to wander, throwing the beam off course, randomly
! The optical timing grating was not securely held down
permitting the machine to become sensitive to its own vibration. The
optical enclosure was not totally blackened , permitting stray laser
beams' splash to interfere with sensors, particularly the grating
sensor which would destroy internal timing and destroy the output
image, just displacing one little scan line, intermittently, just
enough to cause a call out, but not reproducible enough to find and fix
! I carried a black texta with me, so all the little metal clips
and things got made black. This actually helped.
I solved the problem of hum getting into the low level video. It was
nothing more than re routing the main video amplifiers power cabling so
that it followed the same route as a coaxial cable carrying the video
signal, thus eliminating a hum loop being threaded by the stray field
from the power supplies. I performed this fix before ECRM's engineering
manager at the time, I dont know if the
fix ever went into production, not-invented-here
syndrome probably lost this cause.
There was active
circuitry that had no input and no output. There was circuitry that did
absolutely nothing. They were clearly hooks into other options and
projects that never materialized. But even so, redundant and dead logic was
faithfully copied from revision to revision.
now, I feel sorry for ECRM, it was a valiant effort and a good company
trying to make an honest buck. A search on the web reveals that they
still exist! They now produce direct to plate imagesetters and by all
accounts a good product too, and I wish them well.
1983 I attended ECRM at Bedford , Massuchusets ,for a training course,
at the end of which I was offered employment there, however, my view of
the American rat race and my sense of loyalty to my then boss Mr John
Christopher Robins at Xenotron caused me to decline. We had it better in
Australia. I am indebted to my "gonne" toting instructor Mr Bob Patten
(the third!) for his kind, all American hospitality, that showed
me a human and good side to life over "there" , in Australias'
Yep, some of them brought their guns to work. A disturbing sight for me, as such things are rightly prohibited in Oz.
The model 8400 was renamed to the 740 after another printing products company had a typesetter of the same name.
left just before the Autokon 1000 was released to the market, this
model contained a complete redesign of the electronics ,including
microprocessor control and addressing many of the design
deficiencies of its predecessors.
see also The Xentron XVC2
this page was created Tue May 6 18:20:53 EST 2008