Have you ever tried to read a text on your phone under direct sunlight, and the screen is barely legible with little to no contrast?
Industrial applications are frequently exposed to strong external sunlight, which can result in washed-out images and darker screens, causing lowers contrast and blurs that affects the display quality.
To overcome the effect of sunlight and be readable with clear display quality under sunlight, a touchscreen monitor that can be viewed in direct sunlight has to have very high contrast. This high contrast doesn’t exist in any customer grade displays, and is only available as a specialized feature in high grade industrial displays, due to cost. This feature is commonly referred to as Sunlight Readable in touch screen monitors & touch screen panel PCs.
In this blog, we will provide a brief introduction to the technology of Sunlight Readable Touch Screen, and why it is so important for industrial displays that are exposed to sunlight.
What is Sunlight Readable Touch Screen Monitor & Sunlight Readable Display
Sunlight Readable Touch Screen Display is a commercial monitor display designed to be readable and crystal clear under extreme high ambient lighting conditions, including when exposed to direct sunlight.
In typical displays, because the effect of sunlight is much stronger than the backlight of the display, the entire screen will have very low contrast, causing the text to be barely readable.
To overcome the effect of sunlight, a significant higher backlight intensity is required for display screen. Sunlight Readable Touch Screen Display is designed with 7x to 10x the amount of backlight/brightness than standard display monitors, resulting in a much better contrast, even under direct sunlight. Furthermore, Industrial Monitor Direct Sunlight Readable Touch Screen Display contains additional technologies that further enhance the readable of display under the sun, including specialized optical bonding and specialized diffuser.
What is LCD Backlight
A type of illumination utilized in liquid crystal displays is called a backlight (LCDs). LCDs require illumination (either ambient light or a dedicated light source) in order to produce a visible image because they cannot produce light on their own, unlike, for instance, cathode ray tube (CRT), plasma (PDP), or OLED displays. Unlike frontlights, which are positioned in front of the LCD, backlights shine light on the LCD from the side or back of the display panel. Smart phones, computer displays, and LCD televisions all employ backlights to produce light in a way that is comparable to a CRT display. Backlights are used in small screens to boost readability in low light circumstances, such as in wristwatches.
LED backlights
There are two types of LED backlighting for color screens:
white LED backlighting and RGB LED backlighting. White LEDs are most commonly used in notebook and desktop screens and make up virtually all mobile LCD screens. White LEDs are typically blue LEDs containing a broad-spectrum yellow phosphor that emits white light. However, the spectral curve peaks in yellow, which does not match the transmittance peaks of the red and green color filters of the LCD. This shifts the red and green primaries to yellow, reducing the color gamut of the display. RGB LEDs, which consist of red, blue, and green LEDs, can be controlled to produce color temperatures different from white. While LED is becoming the go to for customer applications, LCD is still a much better technology for many reasons.
CCFL backlights
Until about 2010, cold cathode fluorescent lamps (CCFLs) were the preferred backlight for large matrix-addressed LCD panels used in monitors and televisions. Either two CCFLs were placed on either side of the LCD, or an array of CCFLs was placed behind the LCD (see his image of his array of 18 CCFLs for a 40 inch LCD TV). LED backlights are becoming more popular due to the drawbacks of LED lighting, but for industrial applications, LCD is still the go to for many reasons.
Diffusers
For non-ELP backlights to produce the uniform illumination that is essential for displays, the light must first pass through a light guide. The diffusion equation shows that bump density increases with distance from the light source. The light is then reflected towards the LCD screen by a reflector behind the diffuser. The diffuser is on the opposite side of the front LCD screen itself. A white pigmented surface or aluminum foil can also be used as a reflector.
Why is LCD Better For Sunlight readable Display?
LCD technology is commonly used in touch screens that can be read in the sun. A flat panel display known as a Liquid Crystal Display (LCD) makes use of the liquid crystals' ability to modulate light rather than emit it directly.
The LCD backlight systems are made highly efficient by applying optical films such as prismatic structure to gain the light into the desired viewer directions and reflective polarizing films that recycle the polarized light that was formerly absorbed by the first polarizer of the LCD, generally achieved using so called DBEF films. These polarizers consist of a large stack of uniaxial oriented birefringent films that reflect the former absorbed polarization mode of the light. Such reflective polarizers using uniaxial oriented polymerized liquid crystals. The combination of such reflective polarizers, and LED dynamic backlight control make today's LCD televisions far more efficient than the CRT-based sets, leading to energy that is important to many industrial applications.
Additionally, LCD has a variety of benefits that are essential for outdoor industrial installations, a thin profile, light weight, and a higher resolution.
