Whatever operating system powers your phone — Android, iOS, or Windows — it most likely has a liquid crystal display (LCD) screen. Traditionally, LCD screens comprise three distinct parts: A protective glass cover, an LCD that generates colors and displays images, and a circuit that detects touch and taps on the screen (touchscreen). Although emerging technologies, such as OLED, integrate touch sensitivity with the screen, almost all phone screens comprise the same parts, irrespective of the brand or screen resolution.
Let’s examine the three parts that make up cellphone displays in details.
Protective Glass Cover
The outermost part of your phone screen is made of a type of chemically-tempered glass. This glass cover — also called Corning’s Gorilla Glass — is made from aluminosilicate (comprising aluminum, silicon, and oxygen) and some strain of sodium ions. By design, Gorilla Glass is shatter-resistant and scratch-resistant, even when you drop your phone. However, although it is made to be tough and shatter-resistant, Gorilla Glass can still break. This is because, in a bid to reduce size and weight, manufacturers need to make the glass thin (less than 1 mm thickness).
Emerging technologies are looking at lab-made sapphire glass covers as an alternative to aluminosilicate glass screens. However, although sapphire screens are naturally scratch-resistant, they are more expensive, and less shatter-resistant than Gorilla Glass.
Liquid Crystal Display
Most cellphones use LCD screens, as can also be found in computer monitors and TVs. The functions of the LCD screen in cellphones differ from in most TVs. Cellphones often use LED backlights to conserve power and save space, while TV screens use a fluorescent backlight to light their LCD.
Recently, some phones are switching to the organic light-emitting diode (OLED) technology, which generates light internally, and eliminates the need for separate lighting. OLED screens are more power-efficient and flexible, making them suitable for curved phones.
The third part of your smartphone display is the touchscreen, located directly below the glass cover. Your smartphone has a capacitive touchscreen which is a circuitry of little wires that continuously generates an electrical force. When you touch the screen with your finger, you’re technically interrupting an electrical field, and the phone interprets this interruption as a tap. To register a tap on a capacitive touch screen, you’ll need to use a material, such as a padded stylus, that has similar conductivity to a human finger.
Earlier phone versions used an analog resistive touchscreen which has two separate layers. The top layer consists of a plastic film, while the bottom layer is made of glass. When you press the film, it creates contact with the glass layer and completes a circuit. Although they were relatively cheaper to manufacture and could work with input signals from several sources (such as fingernails, gloves, fingertip, or narrow stylus), resistive touchscreens were more fragile and lack the ability to read multi-touch gestures. Today, although pressure-sensitive, resistive touchscreens are no longer common smartphones, devices such as ATMs and car GPS screens still use them.
Essentially, except you use an OLED-display smartphone, these three parts make up your phone’s screen display.