21-06-2012, 04:28 PM
A front screen sensor technology for flat panel medical displays
[attachment=25026]
HOW DO LIQUID CRYSTAL DISPLAYS WORK?
Comparing LCD-based electronic displays to film
Liquid Crystal-based flat panel displays are basically light-valves, acting just like film in front of a light-box, only in this case the film is an electronic medium: the Liquid Crystal Display (LCD).
In electronic displays, the light-box is called a backlight. To make the display thin, it is made of small, tubular fluorescent lamps with a diameter of around 5mm. As with a light-box, the lamps are always on at full power, independent of the actual image content displayed. The backlight thus has no image forming function; it is just there to emit light and send it through the electronic display valves. The image forming element, equivalent to the film, is the LCD panel. Composed of millions of switch-able light-valves, it is possible to construct an image by turning on or off (and variations in between) specific light-valves.
Comparing LCD-based electronic displays to CRT-based electronic displays
Prior to the advent of flat panel displays, the most common technology used for electronic displays was the Cathode Ray Tube (CRT). Although their working principle is identical to that of the well known CRT from the television set at home, medical grade CRTs use precision electron gun optics and high frequency deflection to reach ultra high resolution.
Digital is NOT perfect!
A flat panel display is the closest you can get to a full digital display, but LCDs still incorporate some key operating principles from analog technology. Several issues exist that make LCDs less than perfect (or even un-useable) for medical applications without appropriate compensation and correction.
I-Guard detects and corrects backlight instabilities
The backlight, a kind of light-box with fine fluorescent lamps positioned behind the liquid crystal panel, is an important source of instabilities. The efficiency of these lamps is extremely temperature dependant. The luminance can fluctuate drastically in a short time frame (minutes to hours) due to temperature changes at start-up.
Over a longer time period - it’s entire lifetime - the luminance slowly degrades because the phosphors used in the lamps wear out.
I-Guard, from its position in front of the screen, detects all of these changes and continuously corrects both the short term and long term instabilities (2 times per second).
[attachment=25026]
HOW DO LIQUID CRYSTAL DISPLAYS WORK?
Comparing LCD-based electronic displays to film
Liquid Crystal-based flat panel displays are basically light-valves, acting just like film in front of a light-box, only in this case the film is an electronic medium: the Liquid Crystal Display (LCD).
In electronic displays, the light-box is called a backlight. To make the display thin, it is made of small, tubular fluorescent lamps with a diameter of around 5mm. As with a light-box, the lamps are always on at full power, independent of the actual image content displayed. The backlight thus has no image forming function; it is just there to emit light and send it through the electronic display valves. The image forming element, equivalent to the film, is the LCD panel. Composed of millions of switch-able light-valves, it is possible to construct an image by turning on or off (and variations in between) specific light-valves.
Comparing LCD-based electronic displays to CRT-based electronic displays
Prior to the advent of flat panel displays, the most common technology used for electronic displays was the Cathode Ray Tube (CRT). Although their working principle is identical to that of the well known CRT from the television set at home, medical grade CRTs use precision electron gun optics and high frequency deflection to reach ultra high resolution.
Digital is NOT perfect!
A flat panel display is the closest you can get to a full digital display, but LCDs still incorporate some key operating principles from analog technology. Several issues exist that make LCDs less than perfect (or even un-useable) for medical applications without appropriate compensation and correction.
I-Guard detects and corrects backlight instabilities
The backlight, a kind of light-box with fine fluorescent lamps positioned behind the liquid crystal panel, is an important source of instabilities. The efficiency of these lamps is extremely temperature dependant. The luminance can fluctuate drastically in a short time frame (minutes to hours) due to temperature changes at start-up.
Over a longer time period - it’s entire lifetime - the luminance slowly degrades because the phosphors used in the lamps wear out.
I-Guard, from its position in front of the screen, detects all of these changes and continuously corrects both the short term and long term instabilities (2 times per second).