The home is one of the few areas where CRTs still hold the major display market share (although flat-panel plasma-display panels (PDPs) and large thin-film-transistor liquid-crystal (TFT LCD) are rapidly making inroads), but in the dirty, oily and often wet industrial environment, the CRT has been usurped by flat panel LCD technology.
The advantages of the LCD panel are compact size, weight, robustness, relatively cool operating temperatures and the fact they can be “ruggedised” more easily than a CRT. They also offer the best solution for the high-graphics applications typical of the man-machine interface (MMI) market.
However, it has not been a completely smooth ride for the newer technology. Compared to the venerable CRT, LCDs are perceived as having some disadvantages, notably readability in bright ambient conditions, restricted viewing angle and expense. Faced with the opportunities of the industrial MMI market, however, manufacturers have devoted considerable time and expense to addressing these drawbacks.
Backlighting a standard LCD panel dramatically improves its daylight readability but requires considerable power. To reduce the power demands major LCD-panel suppliers use transflective full-colour panels in their products. As their name implies, these panels work in either transmissive mode (with backlighting) or in reflective mode (using incident ambient light).
Readability can look good in reflective mode, but, to achieve this readability, the display requires incident-light levels approaching full sunlight or at least bright daylight. Unfortunately, running the display in reflective mode in most indoor environments doesn’t produce a readability comparable with, for example, backlit mode in low ambient light.
Another factor that can cause problems is viewing angle. Although there have been improvements, users should expect some limitation or variation of the acceptable viewing angle as displays change from predominantly backlit to reflective mode. Published light-level figures and viewing-angle polar diagrams are a guide, but checking while altering the ambient lighting is the best way to see if the display will function well in a given situation.
Despite the improvements in readability and viewing angle, some industry watchers expect some form of organic LED (OLED) to eventually supersede LCD, and manufacturers have spent years developing these devices. OLED technology is emissive; layered deposition of organic semiconductor materials, rather than the more familiar metallic semiconductors, form light-emitting structures.
After years of development, OLEDs have enough absolute brightness to offer good contrast in bright ambient lighting. They are thin and require no backlighting, and—as the light is emitted from (close to) the surface of the structure—they are efficient, with none of the losses of, for example, an LCD panel in which the light is attenuated as it passes through polarizers and filters. Further efficiency comes from the fact that only the active pixels generate light and consume power; the subtractive structure of an LCD requires full backlighting all the time. OLEDs have a wide viewing angle, and they are fast, active-electronic devices. Full video data rates and operation at low temperatures are well within their switching rates.(1)
OLED displays are not available yet for industrial applications, but are the one to watch for the future.
So what is on offer today? The answer is plenty from scores of first-class Australian and NZ industrial display suppliers. All offer decent ranges of ruggedised displays using the latest LCD technology, and often the choice comes down to the expertise, leadtime, price and after-sales service of the supplier. Here we provide details of the products we have seen in the past few months. (For more comprehensive coverage of new releases, and an archive of hundreds of display products also visit our website at www.electronicsnews.com.au and our sister directory site at www.ferret.com.au)
Kontron’s (distributed by Interworld Electronics ) KFM Series Industrial LCD Monitors are available with 381 mm, 459.7 mm or 541 mm SXGA TFT LCD screens with anti-reflective hardened glass window and can be rack or panel mounted with the exception of of the latter which can only be panel mounted. The front panels are finished in either powdered or stainless steel and the LCDs are covered with a 3 mm thick anti-reflective window. Flicker-free LVDS image quality is delivered in 16 million colours with a brightness of 250 Cd/m2. The monitors are certified according to CE, FCC and GOST-R standards. The degree of protection offered by the front side of a KFM monitor is IP65. These monitors are popular in industrial applications such as in the food industry, where production areas are pressure hosed several times a day.
3M has built MicroTouch Near Field Imaging (NFI) touch technology into its 450 FPD monitors. The projected-capacitive technology enables the monitor to detect touches made by conductive objects - fingers or a conductive stylus as well as through gloves and other potential barriers such as moisture, oil, gels and paints. Sensing circuitry generates a precise profile of a touch using specialised data acquisition and image processing techniques. The MicroTouch ChassisTouch 450 FPD touch monitor is made of strengthened glass with a bezel-to-touchscreen seal. It is based on a laminated construction and carries no mechanically sensitive components. The NFI monitors are certified to both NEMA 4X and IP66 standards.
Designed for harsh conditions
The FPM-3190 from Advantech is a large 482.6 mm colour TFT LCD flat panel monitor specifically designed for industrial applications. It features Direct-VGA signal transmission, which allows a regular VGA control card to be used in the system allowing users to upgrade the display without making changes to their existing system. Its multi-scan function supports SXGA, XGA, SVGA, VGA and text mode and has a built-in feature that auto-recognises the input signal. The stainless steel chassis and the stainless front panel give it NEMA4/IP65 compliance. It supports panel, wall, rack mount or VESA arm and claims a high luminance up to 250 Cd/m2.
The Aydin (Intelligent Systems ) 4218 AMLCD is specifically designed for harsh industrial applications. The TFT panel display can withstand 20G shock and the large 459.7-mm display offers a viewing angle of ± 85°. It operates in humidities ranging from 10 to 80 percent and temperatures from 0 to 50 °C. The display is offered in rack, panel, wall and console mounts and industrial desktop. Front and rear control options are available as is the anti-reflective safety glass (a protective viewing window is standard). Resistive, capacitive or SAW touchscreens are available as options.
For bright-light and outdoor applications, ICP Electronics offers the SRM Sunreadable Series - an enhanced ultra-high brightness TFT LCD colour panel, featuring between 700 and 1750 Cd/m2 and up to 16.7 million colours. The SRM Series is equipped with an auto-dimming kit which allows the display’s brightness to automatically adjust to correspond with the external light source. It is protected against dust and can withstand jets of water from any direction. ICP’s DM industrial series has been designed for indoor industrial environments, such as factory automation, and features a brightness of between 170 and 250 Cd/m2. The monitors’ front panels are resistant to dust and liquid and meet IP65 protection rating.
For rugged environments, Amtex has introduced the 266.7 mm I-SFT 50i.2. The active matrix display operates over an extended temperature range of -25 °C to +85 °C and has an operating shock rating of 100G. It offers VGA resolution and wide viewing angles of ±80 ° horizontal and 45°/-80° vertical. This “Hibrite” model offers a backlight brightness of 500 Cd/m2 with a contrast ratio of 250:1. It has a built-in 12 V dc integrated inverter and a 6-bit RGB input signal.
The Spectra series of LCD screens from ESIS are said to be in the “very rugged” class, suitable for SCADA applications such as process, machine and mining control systems where standard PC equipment may not survive. The display is available is two sizes (304.8 mm and 381 mm) and the LCD has a thick aluminium surround to resist flexing with the front panel extending 12 mm beyond the cut-out dimensions. These screens are sealed against contamination and moisture since the coversheet is sealed to the glass substrate with an industrial grade caulk preventing any wicking of fluid between the coversheet and glass. The AccuTouch screens are not air vented, thereby preventing fluid ingress through an air vent.
Zytronic’s (Transcity ) touchscreens are based on projected capacitive technology where the touch-sensing layer consists of an array of microfine wires that are not visible on a powered display. In a capacitive system, the sensing medium is on the surface of the touch panel. Operating temperature ranges from –35 ºC to +65 ºC with sub zero operation achieved by an integrated heater panel. The panels are said to be unaffected by dirt, moisture and rain, are resistant to contamination and unaffected by harsh cleaning fluids. The Zytouch panels also offer good readability with light transmission of up to 91 percent through a standard sensor.
Sharp has introduced a range of high bright displays, the smallest of which is the 260-mm LQ10D421. It features a wide viewing angle of 120° horizontal and 90° vertical, a brightness of 300 Cd/m2 and a contrast of 100:1. This module is a colour active matrix LCD module incorporating amorphous silicon TFT. The modules are slim and quite lightweight at 635 g.
Further information: Details of suppliers can be found by going to this article at www.electronicsnews.com.au and clicking on links. Reference: 1) “Thin, flat, and low power: The ideal display is (still) just around the corner”, Graham Prophet, EDN Europe 12 June 03.