The display sector is characterized by rapid periods of growth and innovation when competing technologies occupy large portions of the same market space. Cathode ray tube displays were supplanted by the rise of lightweight liquid crystal display (LCD) matrices, later on with light-emitting diode (LED) backlights, and now LCDs are experiencing significant market competition from organic light-emitting diode (OLED) technologies.
Modern display tests for ultra-high definition televisions and handheld digital devices are now regularly performed on multiple, fundamentally different technologies. Images on an LCD display are created using a bank of white LEDs and a layered system of polarizers and colour filters, while QD-LED displays typically reduce the requisite number of colour filters and introduce a layer of red and green photo emissive nanocrystals over a backlight of blue LEDs. OLED technologies meanwhile are fabricated from semiconducting materials arranged in a nanomolecular thin-film structure, which emit light organically when excited with electronic signals.
These radically different technologies are also subject to significant further flux in the coming years, with ongoing research into transparent and flexible display technologies, and direct-view QD technology. Will the landscape of display tests adapt to meet the improving capabilities of the display market?
Performing Display Tests on Modern Technologies
The capabilities of the display market are changing radically, but the requirements of display test and measurement equipment has remained largely the same. Accurate light- and colorimeters or spectrophotometers are still required to assess the optical qualities of a display according to the human eye, whether it uses QD, OLED, or LCD technology.
The light-sensitive diode of a photometer is designed to acquire unique optical responses that are closely matched to the average spectral sensitivity according to the CIE 1924 luminosity function Vλ. Usually, tri-stimulus colorimeters are used to cover additional objective optical values in red and blue spectral areas, providing an accurate assessment of a display’s emission spectra for short, medium, and long wavelengths according to CIE 1931. These measurements provide exceptional wavelength definitions and can be acquired by measuring the whole display or assessing individual pixels or spots from the centre to the edge of the image in-line. Display tests typically also include aspects such as Gamma, response time analysis, contrast ratio and flicker adjustment.
Enhanced measurement arrangements can be prepared for multi-spot measurement of multiple optical parameters with outstanding degrees of repeatability. Smart interfaces have been developed to provide simultaneous analysis of the spectral and radiometric characteristics of a display with exceptional degrees of repeatability.
Display Tests with Admesy Products
Admesy is a leading developer of optical measurement equipment for display measurement technologies. Our ever-improving range of equipment is developed to perform precise measurements of a display’s emissive characteristics and closely match those properties to an objective spectral standard. These include:
- The Atlas 2D imaging colorimeter systems: for comprehensive 2D display tests with luminance and colour measurements adjustable for up to a single RGB pixel;
- The Hyperion colorimeter series: for highly accurate colour, flicker, contrast ratio and response time analysis.
- The Cronus spectro-colorimeter series: a hybrid device that allows spectral measurements and built-in XYZ colorimeter for combined colour, flicker, and contrast ratio analysis with a sample rate of up to 50.000 samples per second.