Adi Abileah is, these days, an independent consultant in display technology, although readers may know him from his time as Chief Scientist at Planar Systems. He gave a very interesting talk on special vertical display application requirements including automotive, aviation, medical and defence.
Each of these applications has special requirements. Automotive displays are based on a wide variety of technologies, including FVDs, EL and OLED as well as LCD and are changing in configuration. In the past, hoods were positioned over the display area to cut down on the effects of high ambient light. The curved glass that is over the displays is designed to reflect light from outside the vehicle away from the driver. Automotive displays often follow the general trends from aviation and there is a move towards centralising the displays further away from the driver and nearer to the windscreen to reduce the time spent in re-adjusting focus and vision when the driver switches from looking at the road to the instruments. Instruments are increasingly supplying numbers rather than using the analogue indicators of the past.
When hoods and covers cannot be used, a lot of attention has to be paid to optical bonding, anti-reflective and anti-glare films to maintain contrast. Each has pros and cons, for example, anti-reflective films can cause problems from fingerprint marks. Countering reflections is a very big part of designing displays for use in high ambient conditions. Another method of boosting performance is to increase brightness to compete with the reflections.
A problem with displays in centre consoles is that sunlight coming into a car and reflecting off a passenger’s white shirt can cause a lot of problems for the driver. There are clear standards for measuring automotive displays and those standards are developing.
The extension of the concept of moving the apparent image is for cars to start to use head up displays (HUDs), as is done in aviation. Abileah went through the requirements for aviation displays both in instruments and in helmet-mounted and head up displays. Helmet mounting is an advantage when the pilot has to look around.
Aviation and military displays are in four categories, head up displays, helmet mounted displays, head down displays and mobile displays. Aviation HUDs are based on beam combiners that combine the light from the display with the cockpit view. Linearity and accuracy has to be extreme, which makes the projection and optical design very critical.
Head down displays, for example in military vehicles, are typically high brightness, high resolution LCDs. Vibration and shock requirements can be very extreme, as can environmental requirements.
Helmet-mounted displays are typically set up in “near-to-eye” configurations, with optics that make the display appear to be 3m or more away.
For ground forces, flexible displays, especially with low power and reflective/transmissive displays are likely to be popular. Foldable displays for electronic maps would be very useful.
Turning to medical displays. Abileah covered the boost in resolution (which shows a clear exponential trend) and complained that 12 megapixel displays were not available to match the image sensors for digital mammography (we were able to advise him about the new 12 megapixel displays from Barco!). Medical modalities include radiography, mammography, computed tomography, magnetic resonance, gamma camera, digital subtraction angiography and ultrasound and each has different requirements in the grey scale levels and resolutions. For radiography, Dicom support is essential and products need to meet different formal standards in Japan, the Americas, Germany and Europe.
A significant trend for the future is the use of displays in operating rooms, where accurate colour is required.