RDS’ business development manager, Mike Fowle, provides an overview of existing display technologies and investigates features and benefits of micro LED displays
TFT LCD is considered a stable and established technology. The ubiquitous TFT (thin film transistor) LCD has been a mainstay for design engineers for over three decades and has been extensively used in a broad range of applications. During this time significant enhancements have included: wide viewing angle technologies including IPS (in-plane switching) and MVA (multi-domain vertical alignment); and high brightness, long-life white LED backlights. TFT displays are now produced with refined manufacturing techniques and high yield rates.
Next comes OLED which offers exceptional optical performance. Much acknowledged OLED (organic light emitting diode) display technology has seen significant investment and commercial success in high volume OEM markets such as flat screen televisions and mobile phones but remains seldom seen in medium-size (5 to 17in) display applications. OLED display technology provides excellent optical performance in terms of deeper, darker black levels, highly saturated, vivid colour reproduction, enhanced contrast ratios and fast response times. OLED technology, materials and derivative development continue apace but OLED displays remain complex and costly to manufacture.
Micro LED is an emerging potential. As a recent display technology development, micro LED is considered by some industry analysts to be a potential long term successor to TFT and OLED display technology. Micro LED is a direct drive, emissive (no backlight needed) display technology, constructed with an array of microscopic (50 to 2µm) LEDs forming the individual pixels. Micro LEDs enable higher image quality in direct emission displays because each pixel is constructed of three subpixels—each composed of a red, green and blue micro LED. Manufacturing costs are reduced due to the simple physical structure of micro LED technology, while resolutions and sizes of micro LED displays can be scaled with relative ease.
Micro LED technology is already being deployed in a scalable tile format to build displays of any size and resolution. Applications include smart watches, handheld tablets and video wall displays.
Micro LED displays have many individual components in comparison to conventional LCD displays. Direct emission micro LED display technology brings advantages to optical performance in terms of high luminous efficiency, increased brightness, enhanced contrast ratios and faster response times. Black levels are also enhanced with defined zones of the display image now appearing completely black, with the ability to create a genuine representation of ‘true black’.
Smaller components, enhanced optical performance, reduced power consumption and the reduced costs of micro LEDs bring new possibilities for many display systems and applications. Micro LED technology promises to be more progressive, offering a display technology that can compete with OLED, with improved brightness, deeply saturated colours and enhanced reliability.