Product category: Monitors
News Release from: Digital View | Subject: Felixtowe and Hong Kong docks
Edited by the Electronicstalk Editorial Team on 17 October 2001
Displays in the dock
Digital View has completed a novel touch screen project which has made full use of the advantages of LCDs in an industrial application.
Until recently, LCD technology has seen relatively little use in the industrial market Essentially, this is because LCDs were originally developed to meet the low-power needs of the laptop PC, rather than the somewhat more demanding requirements of the industrial environment
This article was originally published on Electronicstalk on 2 Jan 2001 at 8.00am (UK)
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Overnight, using LCD panels for industrial applications became a real possibility.
An excellent example of the questions asked of LCDs by the "real world", and how they have begun to be answered, is that of Hong Kong and Felixstowe Docks.
Both are owned by Hutchinson Wampoa (which owns docks across the world), a company which had recognised that, with computer technology in their cabs, crane operators could not only monitor the exact loading positions of individual containers - thus enabling more accurate and faster loading - but could also stack up jobs.
This would result in greater efficiencies across the whole dock.
But bringing computer technology to a dock crane was likely to be no easy task.
The cranes are over 25m high, with a cramped glass bubble, designed to accommodate 24 hour operation, atop a long vertigo-inducing ladder.
Clearly, the computers would be best located remotely.
But this would mean that the only effective way to drive the display would be by using the analog signals of a standard CRT graphics system - and installing CRTs into the crane cab was simply not viable.
This was because space was at a premium in the cab - an already claustrophobic and cramped work place.
Flat panel was the only possibility.
But this introduced another problem.
The cabs are a place where temperatures vary dramatically, and where bright sunlight gives way to pitch darkness, and hard frost to blistering heat.
Hardly a place for LCD technology.
Enter Digital View, a specialist in LCD solutions.
The company had been contacted by Hutchinson to look at possible solutions for both the HK and Felixstowe locations, each with different priorities.
With an office both in HK and the UK, Digital View was well placed, technically and physically, to supply a solution for each.
The first technical issue was a result of the fact that the processing units were to be located some 100m from the displays.
This kept the power requirement out of the cab, and left less equipment to be protected against the specific environmental conditions of the cab.
Crucially, it also left more room for the operator.
But, if flat panel were to be used, this meant there was an interfacing problem.
Why? Because flat panels are digital devices, and digital signals can only be driven over short distances.
True, the latest LVDS digital driver chips were available to extend the traditional 1-2m limitation, but by nowhere near enough.
The only solution was to place a local analog to digital interface card at the monitor end of the display to convert the CRT analogue signal, produced by the PC graphics card, to the digital signal required by the LCD.
Next, it was necessary to decide how the operators were to control the PCs.
As cabs are designed to give the operators uninterrupted fields of vision, it was out of the question to mount the display, and especially a keyboard, where it would cause an obstruction.
Therefore, the display must be mounted at foot level, and would be operated via a touch screen interface.
In itself, adding a touch screen to a flat panel is a straightforward task but, in this case, there was a problem.
A touch screen not only reduces the light coming direct from the display, therefore reducing its brightness but, in bright sunlight, increased reflection from the glass overlay could seriously affect the contrast - and therefore readability - of the display.
In this situation it is important to choose a non-reflective overlay with the highest possible translucency.
So what was the solution for Hong Kong? Actually, Digital View approached the problem by developing a complete LCD monitor with touch screen especially for the application.
The display itself was based on a sunlight-readable colour TFT LCD, as temperature range was not a major concern.
Although extremely hot, the temperature swing in Hong Kong is not nearly as dramatic as that in Felixstowe - you rarely get a frost in Hong Kong.
The LCD - Sharp's latest 300cd/m2 wide-viewing angle unit - was combined with one of Digital View's own analogue controller electronics and signal kit, and used an integrated touch screen.
In effect, the system was a lightweight industrial monitor offering complete protection from water and dust (to IP55).
Felixstowe however was another question.
Temperature range was a real issue, and there was a concern that the more expensive TFT technology would not prove viable.
Also with the sun lower in the sky, reflection and direct sunlight was even more of a problem.
TFT, it was felt, was not the right answer.
However, there was another alternative - transflective STN technology.
A completely different, and older, type of LCD technology, such panels could, with the help of a reflective coating, actually use ambient sunlight to enhance the brightness of the display, rather than rely on the LCD panel backlight to project light through the display and produce the image.
With this arrangement, the greater the direct sunlight, the more readable the display.
Cost saving was another bonus.
Of course, pitching STN against TFT side by side, no user would choose STN for most applications.
This is because it a slower display (unable to react to fast moving graphics) and the viewing angle is poor (so it is only suitable for one person, who must sit pretty well in front of the display).
But, for Felixstowe, it made sense.
There was no intention to use fast moving graphics, and only one operator was required to look at the screen at any one time.
So viewing angle was not an issue.
Thus, STN technology was implemented, incorporating a switch to allow the backlight to be turned off during times of high sunlight, and then back on at night and in other low light environments.
To combat the low temperatures tiny heater pads were built into the monitors, which warmed up the system to an operable limit before the start of the shift.
To overcome the display-PC distance problem, Digital View combined the Sharp LM64P83K 10.4in VGA transflective STN display with its AM-28 28-greyscale analogue controller interface.
This kit was then provided to the integrator (Arcom Controls) to build the complete integrated system.
As a final - but critical - part of the solution, the monitors were then tested for ability to cope with the vibrations caused at the top of the cranes by the containers banging into each other.
This required special mounting plates to be constructed by Digital View.
The tests were a complete success, and the new monitors are now installed and operational all over HK and Felixstowe docks.
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