Hardware · Topic 1 of 13
Display Components and Attributes
Compare LCD panel types (IPS, TN, VA) and OLED, and learn display attributes such as resolution, refresh rate, brightness, contrast and touch input.
- 5 min
- TN is fast and cheap with poor angles; IPS has accurate colour and wide angles; VA has high contrast.
- OLED pixels make their own light, give true black and can suffer burn in.
- LCD panels need a backlight; OLED panels do not.
What it is
A display turns signals from a computer into a picture. Screens differ in the panel technology inside, which affects colour, viewing angle, speed and cost, and in measurable attributes such as resolution and refresh rate.
You need to compare panel types and read a specification sheet to pick the right display for a job.
How it works
Panel technologies
Most flat screens are liquid crystal displays (LCD). An LCD panel does not make light by itself, so it has a backlight, usually made of light emitting diodes (LEDs), behind it.
| Panel | Strengths | Weaknesses |
|---|---|---|
| Twisted nematic (TN) | Fast response, low cost | Weaker colour and narrow viewing angle |
| In plane switching (IPS) | Accurate colour, wide viewing angle | Usually costs more; contrast is lower than VA |
| Vertical alignment (VA) | High contrast and deep blacks | Slower response than TN, angle sits between TN and IPS |
| Organic light emitting diode (OLED) | Each pixel makes its own light, perfect black, high contrast, thin | Costs more; static images can cause burn in over time |
TN suits fast games on a budget. IPS suits design, photo work and shared screens that people view from the side. OLED suits phones, premium laptops and televisions.
Mini light emitting diode (Mini-LED) is still an LCD, but its backlight is made of thousands of tiny LEDs grouped into local dimming zones. Zones behind dark areas can dim while bright areas stay lit, so contrast and peak brightness beat a standard LED backlight. It is not self lit like OLED, so blacks are not as deep as on OLED and a faint glow (blooming) can remain around bright objects.
Key attributes
| Attribute | Meaning |
|---|---|
| Resolution | Number of pixels across and down; more pixels give more detail |
| Native resolution | The panel's real pixel grid; other resolutions look blurry |
| Refresh rate | How many times per second the image is redrawn, measured in hertz (Hz) |
| Response time | How quickly a pixel changes colour, measured in milliseconds (ms) |
| Brightness | Light output, measured in nits (candelas per square metre) |
| Contrast ratio | Difference between the brightest white and the darkest black |
| Viewing angle | How far to the side you can sit before colour or brightness fades |
| Colour gamut | The range of colours a display can show |
| Aspect ratio | Ratio of width to height; 16:9 is common |
| Pixel density | Pixels per inch (PPI); higher density gives a sharper image at the same size |
Common resolutions are 1920 by 1080 (full high definition, FHD), 2560 by 1440 (quad high definition, QHD) and 3840 by 2160 (ultra high definition, UHD or 4K). A higher refresh rate such as 120 or 144 Hz looks smoother than the usual 60 Hz, which helps in games and fast motion. High dynamic range (HDR) support allows brighter highlights and deeper shadows.
Touch and mobile display parts
A touch screen adds a digitizer layer over the panel that senses fingers or a stylus. Most use capacitive sensing, which reacts to the electrical charge of a finger.
Laptop and tablet displays also hold:
- the backlight, or on older panels an inverter that powers a fluorescent lamp
- the webcam and microphone in the bezel
- Wi-Fi antenna wires that run along the frame
- the display cable (a thin ribbon) that passes through the hinge
A dim or dark screen with a faint image visible under a flashlight often points to a failed backlight or inverter, not the panel itself.
Matching a display to a job
Resolution is how many pixels, refresh rate is how often the picture updates, and response time is how fast pixels change. Exam questions test whether you can keep these three apart.
Setting the display
Set the operating system to the display's native resolution and the best refresh rate it supports. Use the right cable for the resolution and refresh rate that you want, since an old cable can limit both.
What to remember for the exam
- TN is fast and cheap with poor angles; IPS has accurate colour and wide angles; VA has high contrast.
- OLED pixels make their own light, give true black and can suffer burn in.
- LCD panels need a backlight; OLED panels do not.
- Use the native resolution for the sharpest image.
- Refresh rate is in hertz; response time is in milliseconds; brightness is in nits.
- FHD is 1920 by 1080, QHD is 2560 by 1440 and UHD or 4K is 3840 by 2160.
- A digitizer provides touch input; capacitive screens sense a finger's charge.
- An inverter or failed backlight can leave a very dim image.
Common mistakes
Confusing refresh rate with response time. Refresh rate is how often the screen redraws; response time is how fast a pixel changes.
Choosing a higher resolution on a small screen without checking scaling. Text can be tiny unless the system scales it.
Running a non native resolution. The image is stretched and looks soft.
Assuming OLED has a backlight. It does not; each pixel lights itself.
Judging a monitor by its stated contrast alone. Panel type and viewing angle also change what the user sees.
Check yourself
Which panel type is best for accurate colour and wide viewing angles?
In plane switching (IPS).
What does a refresh rate of 144 Hz mean?
The screen redraws the picture 144 times per second.
Why does OLED show true black?
Each pixel makes its own light, so a black pixel can switch off completely.
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