Sometimes, while we are reading the screen in the sun, the content shows blurred and the display quality and experience is disappointed.
Why the Display Quality will Decline in the Sunlight?
Generally speaking, it is a light reflection effect.
Normally, in outdoor applicants, the screens are added with a protective lens or touch screen as an outer layer. When the light from the sun reflected by the screen is much greater than the brightness from the screen itself when it hits human eyes, the user will feel that the screen is too dark to see the content on the screen.
The screens are bonded to the LCD screen with an air layer generated in the middle so that three reflective surfaces are formed from the outside to the inside. They are the surface of the touch screen, between the air and the touch screen, and the air and the display. Two reflective surfaces are formed from the inside to the outside, from the LCD screen to the air, and the air to the back of the touch screen.
How to Improve the Display Quality in the High Light Ambiance?
We usually call the display with feature of viewable in high ambient light conditions, such as in the sun, the Sunlight Readable Display.
In many daily activities, people need to read the contents from the screen of their applicants, for example, reading the phone on the street, making the selection from vending machines, outdoor advertising, reading the data from a portable device, and many other outdoor operations. Therefore, the display can provide clear content in high light ambiance is important.
3 Common Ways to Enhance the Display Quality in Daylight
The problem can be mitigated from 3 different perspectives:
High Brightness
The first and simplest way is to increase the brightness of the backlight.
Typical LCD panels’ brightness is between 250 cd/m2 to 450 cd/m2, while their brightness reaching to 800 cd/m2 or higher is considered sunlight-readable, but most sunlight readable displays are 1000 cd/m2.
You can easily find the brightness parameter in the display product description.
Custome the brightness of backlight is the most common method of making an display sunlight readable, which are already used by customers from various fields, like vending machines, kiosks, bicycles, portable devices.
Optical Bonding
The 2nd reflection, from outside to inside, is caused by the air layer between the outer screen and LCD, this layer can be eliminated by using the optical bonding technology when gluing the glass of a display to the TFT LCD cells.
By optical bonding, it eliminates the air layer, which helps provide a clearer image with an increased contrast ratio, or the difference in the light intensity of the brightest white pixel color and darkest black pixel color.
With this contrast ratio improvement, optical bonding addresses the root issue with unreadable outdoor displays. Though an increase in brightness can improve contrast, by fixing the contrast itself, LCD display images in outdoor environments will not be as washed out and will consume less power.
Most capacitive touch displays from Tailor Pixels are produced with optical bonding technology.
Transflective TFT
TFT change the diffuser material between the LED backlight and the LCD pixels to a “transflective” material. So that the incoming light is reflected and used to illuminate the TFT display. It has both “transmissive” and “reflective” modes.
Both modes work together to enhance the display performance, it can display the content in very bright ambience perfectly even without any backlight on the transmissive TFT. By this mean, transflective TFT is more and more popular in the demand of good performance in the environments of high brightness and energy efficient required.
One drawback of transflective LCDs is that they don’t allow for as much of the backlight to pass through the diffuser material, so in low light conditions the LCD does not appear as bright as normal LCD.
It is commonly used in ebike meter, epaper and reading device.
