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Tech Talk: OLED, Gorilla Glass and other screen terms explained Aug 20, 2019

KeBlam , Aug 20, 2019 :

Hi all. Kenny (@KeBlam) and Nikolaus (@nmatheis) here to take a deeper dive into one of our favorite features of OnePlus phones, the display.

If you think about it, the display is the part of your OnePlus you interact with the most. So what are some of the characteristics that give us a fast and smooth experience during all those interactions?

Here are the ones we'll cover in our post today:

1. Display Types (LCD vs AMOLED)
   
2. Refresh Rate
   
3. Brightness Range
   
4. Color Space
   
5. Resolution
   
6. Pixel Density
   
7. Screen size
   
8. Screen-to-body ratio
   
9. Types of Glass
   
10. Flat vs Curved glass

On a more intimate level, there are many tactile interactions you have with the display - tapping, gliding, pinching, swiping. Not only does the display need to look good in various environments, it needs to feel good as we physically interact with it.

For those of you with a OnePlus 7 Pro, take a deeper dive into the technology and specifications for this groundbreaking display over at DisplayMate (LINK).


DISPLAY TYPES

LCD



A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals. Liquid crystals do not emit light directly, instead using a backlight or reflector to produce images in color or monochrome. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden, such as preset words, digits, and seven-segment displays, as in a digital clock. They use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements.

LCD displays are typically used in lower-tier smartphones, although some flagships do still use LCD displays.


OLED/AMOLED



An organic light-emitting diode (OLED or Organic LED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. This organic layer is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, portable systems such as smartphones, handheld game consoles and PDAs.

An OLED display works without a backlight because it emits visible light. Thus, it can display deep black levels and can be thinner and lighter than a liquid crystal display (LCD). In low ambient light conditions (such as a dark room), an OLED screen can achieve a higher contrast ratio than an LCD, regardless of whether the LCD uses cold cathode fluorescent lamps or an LED backlight.





There are two main families of OLED: those based on small molecules and those employing polymers. Adding mobile ions to an OLED creates a light-emitting electrochemical cell (LEC) which has a slightly different mode of operation. An OLED display can be driven with a passive-matrix (PMOLED) or active-matrix (AMOLED) control scheme. In the PMOLED scheme, each row (and line) in the display is controlled sequentially, one by one, whereas AMOLED control uses a thin-film transistor (TFT) backplane to directly access and switch each individual pixel on or off, allowing for higher resolution and larger display sizes.


AMOLED displays are used for higher-tier smartphones and provide a crisp, colorful, high-contrast display that gives the end user a more immersive experience when compared to LCD displays.

Refresh Rate

Refresh rate is measured in Hertz (Hz), which is a common measurement for cycles per second. Here, the cycles are the number of times the image on the display is redrawn every second. The higher the refresh rate, the smoother the transition as the image changes on the display. Most phones have a refresh rate of 60Hz. The OnePlus 7 Pro has a refresh rate of 90Hz which makes a noticeable difference in how smooth scrolling and transitions appear on the screen. The Razer Phone's display clocks in at 120Hz, primarily aimed at the gaming market.

Brightness

Nits are used to describe the brightness of displays, where one nit is equal to one candela per square meter and one candela is approximately the brightness of one common wax candle.

The OnePlus 7 Pro has an exceptional brightness range of 2 nits with the brightness slider set to minimum brightness in areas with low ambient light intensity to 583 nits for an all-white screen in areas with high ambient light intensity and with automatic brightness turned on.

Color Space

Think of phone's color space as the number of unique colors it can draw upon to create images. AMOLED displays have a larger number of colors to draw upon which gives us the rich, saturated colors many flagship phones are known for. But what if you don't want dayglow colors. What if you want more accurate colors. That's where using predefined color spaces comes into play. For instance, the OnePlus 7 Pro has three pre-defined color spaces that help maintain accurate color by conforming to color space standards. These are sRGB, Display P3, and AMOLED Wide Gamut.

OnePlus 7 Pro Color Space (from DisplayMate)



sRGB is the Standard Red Green Blue color space. It's widely used but has the least colors available to draw images versus the alternatives. As such, it looks duller but is the safest bet for maintaining color accuracy.

Display P3 is a newer standard color space derived from DCI-P3. The original DCI-P3 color space was designed for digital movie projection. Display P3 retained the overall color space but shifted the white point to 6500 Kelvin to maintain consistency with computer displays. Display P3 has a larger color space than sRGB, and selecting Display P3 gives a more vibrant yet still very natural image.

AMOLED Wide Gamut lets your phone use all colors the AMOLED display can draw which results in the rich, saturated colors many of us normally associate with AMOLED displays. Some really like this while others find the colors oversaturated.

One awesome feature of the OnePlus 7 Pro is that the Natural color mode had automatic color management built in. That means that when Natural is selected, the phone automatically detects the color space associated with any image and switches to that color space. The 7 Pro also has extremely high color accuracy, with a perfect rating from DisplayMate on color accuracy. Working together, these two features help ensure you see the image as it should be seen without ever having to intervene. Handy!

Resolution

Now, there’s definitely more than 3 versions of ‘HD’ or high-definition, but there are 3 that we would love to cover! To start, these letters just describe or illustrate how many pixels there are on the screen or in videos! First off is HD, which is around 720p, is the current minimum when it comes to the screen. A bit higher than that is 1080p, or FHD, which generally, when accompanied by a basic 16x9 aspect ratio monitor or phone, will have 1,920 x 1080 pixels. And one more above that (you probably guessed it!) is QHD, or Quad High Definition, which is four times the standard 720p HD; meaning that you can fit 4 times the amount of pixels into a screen of the same size!

Pixel Density



Pixel Density is measured in Pixels per inch (PPI). The real world impact is the amount of detail and sharpness of what's being displayed on the screen. As illustrated in the graphic above, the higher the pixel density, the less pixelation and greater detail and sharpness. There's a point at which increasing pixel density no longer matters based on the limits of human vision at defined distances, but scientists are still trying to figure this out.

Screen Size

Now, for all who doesn’t know or if you’re simply refreshing your memory, the screen size is measured from corner to corner; the weird thing is, it’s measured by the diagonal rather than just base times height, like what I learned in grade school! (I thought the same when I first heard that too!)

So in this case, if you’re talking about OnePlus 7 Pro’s screen size, it would be measured from one diagonal to the opposite, which in this case, would be around 6.67 inches! And the display resolution is measured in pixels. Clearly, with 6.67 inches of screen space an QHD+, you’re rocking an amazing movie experience and I hope you enjoy!

Screen to Body Ratio

Well, before we tackle the screen to body ratio, we must learn what a ‘bezel’ is! It’s not a jewel, nor is it a type of candy! (And for all the millennials like me, it’s not a game!) But a bezel is the name of the frame around the displays, like on both TVs, smartphones, etc. We’re currently hitting an age where everything is getting closer and closer to a bezel-less state, meaning that the screen-to-body ratio is nearing 100% (though it probably won’t hit that anytime I’m alive!) With the same measuring method of measuring the screen size, we would compare both numbers of the body as well as the screen to get a clean screen-to-body ratio! In the case of the OnePlus 7 Pro, it’s flaunting a stunning 88.4%; I mean that’s amazing! We’ve came SO far!

Type of Glass

Now, for those of you who drop their phones a lot (me included), this one's for you: regular tempered glass versus gorilla glass!

To start, tempered glass is heated to an extreme temperature then cooled down with blasts of cold air, thus allowing the glass to strengthen and become harder! However, this is definitely the cheapest option nowadays!

Currently, there is Gorilla Glass which is widely used among smartphone companies due to its durability, scratch resistance, etc. Started in 2007, Gorilla Glass has gone through many iterations to get to where it is now! Similar to the tempered glass, Gorilla Glass undergoes an extreme temperature then it undergoes a compressive stress by utilizing the 'ion-exchanging process'.

The OnePlus 7 Pro is sporting a gently curved Gorilla Glass 5! So far, even after dropping my phone countless times, it's still fully functional and working smoothly!

Flat vs Curved

The age of the curved screen all began when a flagship smartphone company, Samsung, decided to launch a smartphone with a curved display. With great approval and support, the phone was a great success and paved the way for curved displays for many different smartphone companies!

The OnePlus 7 Pro is the first OnePlus phone to have, and even ROCK, the curved display! With it, the curved displays allows for functionalities such as horizon lighting and even adds a new dimension for future smartphones to really experiment on! Although both curved and flat have their advantages, I am growing to like the curve display more and more!