1.2 Compare & contrast the display components of mobile devices

Question 1

2 common types of displays used in mobile devices?

Answer 1

• LCD
• OLED

Question 2

Meaning of LCD?

Answer 2

Liquid Crystal Display

Question 3

Meaning of IPS?

Answer 3

In-Plane Switching

Question 4

Meaning of TN?

Answer 4

Twisted Nematic

Question 5

Meaning of VA?

Answer 5

Vertical Alignment

Question 6

Meaning of OLED?

Answer 6

Organic Light-Emitting Diode

Question 7

What do LCD pixels consist of?

Answer 7

Subpixels with their own transistor to control its intensity

This creates the display’s color range

Question 8

Meaning of TFT?

Answer 8

Thin Film Transistor

Question 9

3 main types of LCD TFT technology?

TFT technology is a type of LCD technology that uses thin-film transistors to improve image quality and performance

Answer 9

• TN
• IPS
• VA

Question 10

How do TN TFTs work?

Answer 10

Uses crystals that twist or untwist

It twists/untwists in response to the voltage level

Question 11

Advantage of TN TFTs?

Answer 11

Faster response times

Question 12

What does fast response times help reduce?

Answer 12

Ghosting & motions trails in high frame rate input

Question 13

What is refresh rate?

Answer 13

Speed at which the whole image is redrawn

Question 14

What is refresh rate measured in?

Answer 14

Hertz (Hz)

Question 15

What should the refresh rate be a multiple of?

Answer 15

Video frame rate

i.e. if a vid has a framerate of 30fps, its ideal for the display to have a refresh rate of 60Hz (30fps * 2 = 60Hz). This synchronization helps ensure smoother & more consistent motion on the screen, reducing issues like stuttering or tearing

Question 16

What is response time?

Answer 16

The time taken for a pixel to change color

Question 17

what is response time measured in?

Answer 17

Milliseconds (ms)

Question 18

How do IPS TFTs work?

Answer 18

Using crystals that rotate

Question 19

Main benefit of IPS TFTs?

Answer 19

Better color reproduction at wider viewing angles

Question 20

What type of LCD is best for gaming & graphics/design work?

Answer 20

IPS

Question 21

How do VA TFTs work?

Answer 21

Using crystals that tilt

Question 22

Main benefits of VA TFTs?

Answer 22

Has a wide color gamut & best contrast-ratio performance

i.e. where a high-end IPS panel might support a 1200:1 contrast ratio, a VA panel would be 2000:1 or 3000:1

Question 23

What is contrast ratio?

Answer 23

Difference in shade between black & white pixels

Question 24

Main drawback of VA LCDs?

Answer 24

Viewing angles are worse than IPS & response times are worse than TN

This makes a VA panel more prone to motion blur & ghosting

Question 25

What are modern TFT LCDs illuminated by?

Answer 25

LED backlight

Question 26

What type of LED arrangement is used on most phone/tablet screens?

Answer 26

Edge lighting arrangement ## Footnote The LEDs are positioned at the screen's edges, with a diffuser ensuring uniform brightness.

Question 27

What backlight did older laptops use?

Answer 27

CCFL

Question 28

Meaning of CCFL?

Answer 28

Cold Cathode Fluorescent

Question 29

What power do CCFL bulbs require?

Answer 29

AC power

Question 30

Why do CCFL-backlit laptops need an inverter?

Answer 30

To convert DC power to AC power

Question 31

How do OLEDs work?

Answer 31

Each pixel has its own LED, requiring no backlight

Question 32

4 benefits of OLED displays?

Answer 32

- Better contrast ratios - Thinner - Lighter - Consumes less power

Question 33

Which display type can be curved to different shapes?

Answer 33

OLED

Question 34

2 main drawbacks for OLEDs?

Answer 34

- Lower brightness than LCDs - More susceptible to burn-in

Question 35

What is a burn-in?

Answer 35

When LEDs retain an image due to displaying a static image for many hours

Question 36

Purpose of digitizers/touchscreens?

Answer 36

Converts analog input to digital instructions

Question 37

What kind of digitizers do modern mobile devices use?

Answer 37

Capacitive digitizers

Question 38

What do capacitive digitizers support?

Answer 38

Multitouch ## Footnote gestures like "pinching" the screen can be interpreted as events & responded to by software in a particular way

Question 39

What does airplane mode do?

Answer 39

Disables some/all wireless features | Cellular data, Wi-Fi, GPS, Bluetooth, & NFC ## Footnote On some devices, some services can be selectively re-enabled while still in airplane mode