Optrex’s thin-film transistor (TFT) LCDs offer viewing areas up to 170º. The displays incorporate In-Plane Switching (IPS) technology, which aligns the liquid crystal cells in a horizontal direction so that the crystal molecules move parallel to the panel plane instead of perpendicular to it, reducing the amount of light scattering in the matrix.

With the development of digital signal processing (DSP) technology, medical monitors have evolved from the old analog versions, into digital multiparameter monitors that can track many different vital signs at once, with the added advantages of miniaturization and portability. Devices such as defibrillators, cardiac monitors, vital signs monitors, and full-clinical-parameter bedside and portable monitors require many capabilities to be integrated into a single display and demand that the information displayed be clear, crisp, and easily readable. Key to their effectiveness is the liquid crystal display (LCD) that displays the critical information they provide.

Medical devices present a special set of requirements for the LCD. The LCD needs to provide high contrast, high resolution images, and data, as well as resistance to glare in high-ambient-light environments such as ambulatory surgical units, emergency rooms, operating rooms, and intensive care units. Portable medical devices must provide a bright, long lasting image when powered by batteries. Displays incorporated into devices used in emergency vehicles must be able to withstand extreme temperatures, shock, and vibration.

Active Matrix TFT (thin-film-transistor) LCDs can handle the high level of content required by medical displays. They provide integrated, all-in-one monitoring capabilities that can show waveforms, color-coded prioritized alarms and menu functions with online help features, while providing exceptionally high contrast, color saturation, and luminance, as well as a range of performance enhancements.

Improving the human-machine interface

TFT LCDs have become the defacto standard in medical displays, displacing the large, bulky, heat-generating CRT (cathode ray tube) monitors that were used for many years. Most medical diagnostic devices utilize TFT LCDs in the size range of 6.5 in. to 19 in. diagonal, and these displays have been incorporating a number of technological advancements that enable them to display more information and make it easier for medical professionals to read, view, and interpret.

Example of 12.1” diagonal TFT LCD patient monitor with 16:9 wide format display.

Today's medical monitor LCDs are thinner, more lightweight and brighter than ever before. Increased brightness - up to 1,500 cd/m2 (or “nits”) - with higher contrast ratios enable displays to provide better legibility and image clarity in high ambient light environments where surface reflections can degrade contrast by reflecting the ambient light. Another tool is an anti-reflective (AR) surface. This is a vacuum deposited thin-film, anti-reflective optical coating on the front polarizer for reducing specular reflections from the surfaces of optical substrates that dramatically improves high-ambient-light legibility and image clarity. The AR coating reduces the surface reflectivity of the LCD panel to ~1%; compared to the 6 to 12% reflectance offered by a normal anti-glare surface, without the need for a high-power backlight, no increase in heat dissipation, and no decrease in luminance or contrast. There are a number of anti-reflective optical coatings that can be applied by Value-Added Resellers (VARs) after the LCD has been manufactured and shipped. However, an AR coating that is integrated into the LCD at the factory where it is manufactured is generally considered to be more reliable.

A super high-bright LCD in the range of 1,000-1,500 nits with a 700:1 contrast ratio, plus AR surface coating will remain clearly legible over a wide operating temperature range (-20° - 70°C) in all high-ambient-light environments from the Emergency Room to the OR.

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