One of the biggest advantages of E Ink display, that of being eye-friendly is all too well known. However, many still seem to have some reservations with the front light feature which they easily confuse with backlight technology. Many even believe both to be similar and have the same negative effect on our eyes even though the reality is completely different. Read on to find the truth behind backlight and front light technology.
Now, going by their inherent working principle, OLED or LCD displays have a light source behind them that illuminates the content on the screen, thus making it possible for us to see what is on the screen. Put another way, it is light emanating from the display that reaches our eyes, which creates the image of what is on the screen in our eyes, thus enabling us to see things on the screen. All of this happens in real time, which makes sure we are able to catch up with even fast-moving scenes, be it in a movie or in a game. It is also for this reason that we refer to LCD or OLED as emissive displays because they emit light of their own which is part of how they are designed to operate.
However, going by the nature of our eyes – it is all about the presence of rod cells and cone cells in our eyes and how having more rod cells enables owls to see things distinctly at night while the converse is true of us – we need to have the light incident on objects that don’t have a light source of their own for us to see them. It is the same with E Ink displays which don’t have a light source of their own and hence need ambient lighting to illuminate the display so that we are able to see it. It’s how we see the everyday objects around us. It is also for this reason that E Ink displays, or for that matter, all e-paper displays are considered reflective displays. So, the more the external light is, the greater is going to be the visibility of the E Ink displays. This is also the reason E Ink displays are perfectly readable even in direct sunlight while emissive displays look washed out.
So, does that mean E Ink devices have no application at night or in dark conditions? Unfortunately, yes though this is also where front light technology comes into the picture. To mitigate the issue of E Ink displays being unreadable in the absence of external light, manufacturers hit upon the simple yet highly effective solution of introducing enough lights to illuminate the display. In effect, these are a string of tiny LED light sources that are placed underneath the bezel and along the side of the E Ink panels. When in operation, the light from these LED bulbs acts to light up the display so that we get to see the contents of the screen.
So, in effect, the front light is fundamentally different from the backlight as the display does not emit any light as such. It’s just that there are lights introduced that illuminate the display externally. Being under the bezels, users never get to have an inkling of the existence of such lights either. Also, this is fine with most e-reader devices with E Ink displays that typically have less than 7-inch sized displays. The real challenge is to have the display illuminated in large sized E Ink devices such as e-notes which can stretch to even 13.3-inch size as well without causing any dark patches as such.
Fortunately, manufacturers have done a fine job so far. Take for instance the Max Lumi or the Max Lumi 2 e-notes with 13.3-inch E Ink displays. Boox said they have managed to achieve the highest illuminance uniformity with both, which means the external light sources light up the display evenly. The Dasung Paperlike monitor with its 25.3-inch E Ink display is perhaps the biggest to have a front light feature. The new 11th-gen Kindle Paperwhite 2022 model comes with a 17-LED array, which is a huge improvement over the 5 LEDs that its predecessor came with.
Yet another area where E Ink display scores over its emissive counterparts, is the amount of blue light these emit. Blue light incident on our eyes can have varying degrees of effect on our physical health. These include macular degeneration so that our eyes end up being damaged over prolonged exposure to blue light. Those can also disrupt our sleep pattern when our eyes are subjected to blue light at night. We are subjected to blue light emission when viewing devices such as smartphones, tablets, smartwatches, or even e-readers having E Ink displays. The only silver lining here is that E Ink displays have less of it and are hence safer than other displays.
With a keen interest in tech, I make it a point to keep myself updated on the latest developments in technology and gadgets. That includes smartphones or tablet devices but stretches to even AI and self-driven automobiles, the latter being my latest fad. Besides writing, I like watching videos, reading, listening to music, or experimenting with different recipes. The motion picture is another aspect that interests me a lot, and I'll likely make a film sometime in the future.
