Enclosures
New standard size for industrial displays from Sharp
The 16:9 format 7 inch diagonal screen is emerging as the new standard for numerous portable test, measurement and input devices spanning all industrial sectors - logistics, transport, medicine, vehicle manufacturing and repair, the hotel trade and catering, etc - and various consumer applications such as pocket PCs, media players and electronic picture frames.
To cLED 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.