A traditional CMOS interface requires a minimum of six data lines for each R, G, B primary color, for a total of 18 data lines. Each line will be driven by a 3.3 V voltage. It is a huge voltage swing, and generates problems with EMI. To address this problem, LCD manufacturers are offering displays with Low Voltage Differential Signaling (LVDS) interfaces, a low-power, low-noise differential technology for high speed transmission. Optimized for point-to-point configurations in telecom, datacom, peripherals, and displays, LVDS delivers the bandwidth necessary for driving large data rates over PCB and cable with low power and low EMI.

A complementary technique is Reduced-Swing Differential Signaling (RSDS), integrated inside the display as the interface between the timing controller and the column drivers. RSDS is a signaling standard that defines the output characteristics of a transmitter and inputs of a receiver along with the protocol for a chip-to-chip interface between flat panel timing controllers and column drivers. The RSDS bus provides reduced bus width, low power dissipation, low EMI generation, high noise rejection (to maintain signal image) and high throughput (which enables high-resolution display).

New developments in backlighting LCDs

LCDs need to be backlit, and the quality of the displayed image is heavily dependent on the backlighting unit (BLU) and the power supply driving it. For many years, TFT LCDs were backlit by cold cathode fluorescent lamps (CCFLs) powered by DC-AC inverters. But in the last few years, more and more TFT LCDs are using HB (high brightness) LED-based BLUs powered by LED driver circuits.

HB-LED backlights offer numerous advantages over CCFL BLUs, including no warm-up time at low temperatures, lower power consumption, higher dimming ratios, and because they do not require high-voltage and high-frequency inverter circuits, significantly reduced electro-magnetic interference (EMI). And since LED backlights contain no mercury, these displays offer a more environmentally friendly or “green” option. LEDs are less fragile and more reliable than CCFLs, and won't degrade if operated for long periods of time, such as the 24/7 operation demanded of a bedside patient monitor. Average lifetime is 60,000 hours, and the wide range dimming capability of LEDs offers a valuable advantage for medical displays, which must be legible in bright daylight as well as in the subdued lighting environment of nighttime operation. That is why more and more LCD manufacturers such as Optrex are offering a wide range of LED-backlit TFT LCDs in display sizes ranging from 2.0- to 15.0- in. diagonal, with a variety of resolutions from which to choose.

Another advancement that been integrated into LED-backlit TFT LCDs by Optrex is Natural Color Matrix (NCM) technology, a patented color transformation algorithm implemented in the hardware that provides real-time on-the-fly processing to precisely match the colors specified in a data source for exceptionally vivid color reproduction. The difference NCM brings to LCD applications is immediately apparent to the eye in the vivid color renditions provided by the technology, as well as crisp text and artifact-free motion video.