PixelBright: Anti-Reflective LCD Screens versus Anti-Glare LCD Screens
In school we learned that the speed of light in a vacuum is a constant; the “C” in Einstein’s theory of relativity E=MC2. “C” represents the speed of light which is constant at 299,792,458 meters/second traveling through a vacuum. The speed of light, however, is slower through all other mediums. For example, the speed of light through air is 299,702,547 meters/second while the speed of light through water is 224,900,569 meters/second.
As you can see the speed of light changes when it transitions from one medium to another medium through which it is traveling. For example, when light transitions from traveling in air to water, it slows down which will cause it to reflect (bounce) and refract (bend). We have all seen 1) our reflection in the water as well as 2) the appearance of a bent stick that was placed in water. Of course the stick was not bent, but the light reflecting off the part of the stick that was under the water appeared bent when it transitioned from water to air on its way to our eyes since light travels slower through water than air. You can also think of this in terms of resistance, water has a greater resistance to the passage of light, therefore light travels slower in water than air. As you can see from the above example, light will reflect and refract when transitioning between two different mediums whether it is air to water or air to surface of an LCD screen.
Scientists have calculated a factor for many materials which can be used to determine the speed of light through these materials called the Refractive Index. Here are some sample refractive indices:
|Medium||Refractive Index||Therefore, the speed of light through this medium is ...|
|Liquid Carbon Dioxide||1.2000||249,827,048 m/s|
|Ethyl Alcohol||1.3600||220,435,630 m/s|
|Sodium Chloride (Salt)||1.5440||194,166,099 m/s|
To calculate the speed of light through any of these materials, simply divide the speed of light in a vacuum (299,792,458 meters/second) by the refractive index of that material as can be seen in the right hand column of the table above. When light transitions between materials with different refractive indices you have a condition referred to as a “refractive index mismatch.” During a refractive index mismatch when light meets the boundary of a different medium (i.e. air to water or air to LCD screen surface), the behavior of light will change by 1) reflecting (bouncing), 2) refracting (bending) and/or 3) being absorbed. In reality, light will do all three above (reflect, refract and be absorbed), however, to varying degrees based on the type of medium.
The point of this background information is to explain how external ambient light (i.e. sun, lamp or indoor lighting) traveling through the air will react when it hits the surface of an LCD screen. The aim of an LCD screen engineer is to minimize the reflection of this ambient light using different LCD screen surfaces. These LCD screen surfaces that engineers use to reduce reflection are called polarizers or polarizing film and can differ based on chemical composition (the new anti-reflective high-gloss surface) or based on physical profile (traditional anti-glare rough matte surface).
Most LCD screens use an anti-glare (AG) treatment on their top surface to diffuse the reflected light from external lighting sources. This is also true of some older CRT monitors. This treatment consists of laminating a matte (rough) surface layer to the LCD. When light hits this rough surface it bounces off at different angles which reduces the intensity of light reflecting off of the surface and hitting your eyes. While this reduces the intensity of light, it does, however, leave a hazy image of the reflection which may block the onscreen image. Unfortunately, this treatment also distorts the image generated by the LCD.
|Traditional LCD with Anti-Glare Surface Treatment|
|Behavior of Light (Ambient) Reflected by LCD Screen||Behavior of Light (Image) Generated by LCD Screen|
Advantage: 1) Reduced intensity of reflected light.
An anti-reflective LCD screen does not have a rough matte anti-glare surface. Instead, it has a coating of an anti-reflective (AR) chemical (magnesium fluoride) that actually reduces reflected light by lowering the Refractive Index of the surface of the LCD panel to a number closer to that of air. This process is known as index matching. This reduces the reflection and refraction of ambient light as it hits the surface of the LCD display. Also, because the surface of an anti-reflective LCD has a smooth gloss finish, the image is crystal clear rather than distorted.
|New LCD with Anti-Reflective Surface Treatment|
|Behavior of Light (Ambient) Reflected by LCD Screen||Behavior of Light (Image) Emitted by LCD Screen|
|Advantage: 1) Reduced intensity of reflected light; not as much, however, as anti-glare. 2) No image distortion. 3) Higher contrast. 4) Wider viewing angles. 5) Colors are more vibrant.|
Anti-reflective LCD screens have many advantages over traditional anti-glare LCD screens which have historically been used in laptop computers. Advantages of anti-reflective LCD screens include:
- Sharper contrast
- Crisper images
- Colors that are richer
- Wider viewing angles
- No reflected hazy image
The advantages of anti-reflective LCD screens over anti-glare LCD screens are simply the result of using a smooth high-gloss surface. A high-gloss surface allows the light from an image to be directly transmitted to the viewer’s eye without being diffused. Diffused light blurs the crispness of an image, blurs the richness of colors and reduces the darkness of the darkest of black pixels thereby decreasing contrast. Contrast ratio (CR) is the measurement of the difference in light intensity between the brightest white pixel and the darkest black pixel.
In addition, viewing angles are superior for anti-reflective LCD screens. Viewing angle is defined as the number of degrees measured from a line perpendicular to the plane of the display in which the display is readable. This is usually defined as the angle at which the contrast ratio (CR) is greater than 10:1. As can be seen in the diagram below, the contrast ratio decreases from the maximum contrast ratio at the perpendicular axis as the angle increases. Hence, the greater the contrast ratio on the perpendicular axis the greater the angle will be where the contrast ratio is 10:1. See diagram below.
|Viewing Angles of Traditional Anti-Glare and New Anti-Reflective LCD Screens|
|Behavior of Light (Image) Emitted by Anti-Glare LCD Screen||Behavior of Light (Image) Emitted by Anti-Reflective LCD Screen|
In the past, LCD screens were only available with an anti-glare surface. Nowadays, consumers have the option of purchasing an LCD screen with an anti-glare surface (rough matte) or anti-reflective surface (smooth high-gloss) depending on the users’ environment.
Both anti-glare and anti-reflective LCD screens serve a distinct purpose. Anti-glare LCD screens may be better suited to office environments, where spreadsheets, word-processing, and similar tasks are the norm - along with many light sources and less flexibility in screen placement. Anti-reflective, on the other hand, may be better suited for graphics, gaming, and multimedia applications - like watching DVDs. While anti-reflective high-gloss LCD screens may seem superior in all facets, they are better suited in indoor environments where ambient light conditions are not as bright. This way the user gets ambient light reflection reduction without sacrificing any image quality. Anti-glare, on the other hand, may be better suited to the outdoors or indoor environments with brighter or direct light. In this situation, the user may be better off sacrifice image quality for maximum ambient light reflection reduction.
Ultimately, this comes down to each user's personal preference. Every user is different, and the best way to determine which screen type is best for you is to stop by your local consumer electronics retailer to see them both for yourself.
You have three different opportunities to purchase high-gloss anti-reflective screens from us:
|Option:||Price for you:|
|You have a non high-gloss screen. You may send it in to us to be re-polarized.||$100 + shipping|
|You're purchasing a replacement of a non high-gloss screen from us. You may upgrade it to high-gloss.||$50 + screen price|
|You're purchasing a replacement of a high-gloss screen from us.||$0 (already included in purchase price)|
The PixelBright high-gloss finish can be added to any screen in our inventory, as an upgrade. Also, you can send in your laptop for us to refinish its screen. On the other hand, many of our brand-new screens have a high-gloss finish by default. These links take you to lists of such screens (screens may appear by laptop model or by screen part number):