New standard size for industrial displays from Sharp

To cover the entire range of applications, Sharp is therefore unveiling a series totalling five industrial standard 7 inch TFT LCDs in the first half of 2010. The spectrum ranges from the robust screens of the more mechanically resilient Strong2 class with extended temperature range from -30 to 80°C to a light type LQ070Y3DG3A variant, with an operating temperature of -20 to 50°C which is designed to be more suitable for consumer applications. This display is also available as a touch screen model (type LQ070Y3DG3B) boasting very good optical properties: with 300 cd/m² it possesses comparatively high brightness and is every bit equal in terms of contrast to its non touch screen sister model. The TFT LCD is also impressively slim, at 7.1 millimetres being only 1.1 millimetres deeper than the variant without the touch screen unit (LQ070Y3DG3A).

LED backlighting: easily dimmable and robust with low voltage

In addition to the 800 x 480 pixel resolution, what the five new 7 inch industrial displays have in common is their LED-based backlight. Compared with conventional CCFL backlights, one of the principal advantages of LEDs for industrial applications is their extremely rapid responsiveness and good dimming qualities. This makes it easy to control the brightness of the display as a function of the ambient light using photodiodes to automatically adjust the display’s brightness so that legibility remains consistently good even in frequently changing light conditions.

A further plus point of LED backlighting is the low voltage, direct current power supply, which reduces EMI behaviour while reducing system complexity since measures to protect against high-voltage can be dispensed with.

Mechanically as well, LED backlights are beneficial. With a depth, depending on model, of between only 6 and 9 millimetres, Sharp’s new 7 inch TFT LCDs have less than half the depth of comparable CCFL variants. This is accompanied by greater mechanical robustness, LEDs being far less fragile compared with the glass bodies of cold cathode tubes. This simplifies the mechanical design and increases ruggedness.

Thermal management determines suitability for industrial use

By virtue of their technology, LEDs are clearly superior to CCFLs at low temperatures; at ambient temperatures below zero degrees Celsius LED backlights can sometimes achieve a life of 200,000 hours, delivering their full light output the moment they are switched on. At higher temperatures however, LEDs are sensitive. The generation of large amounts of heat, occurring locally in the vicinity of the illuminants, must be effectively evacuated as it can damage the LCD panel and backlight itself, considerably reducing their life. Consequently, Sharp has developed a special chassis for LED backlit industrial displays in which the backlighting LEDs are linked thermally directly with the mechanical parts of the module. Waste heat is thereby vented effectively through the rear of the display into the surrounding area so that no harmful heat accumulates, even at high ambient temperatures. The 7 inch series Strong2 display is therefore designed, as are all Strong2 displays, to be operated in environments ranging from – 30 to 80°C, achieving a life of 50,000 hours in the process.