3.1 - Display Types

LCD Advantages

Lightweight

Relatively low power

Relatively inexpensive

LCD Disadvantages

Black levels are a challenge

Requires separate backlight

Florescent, LED, etc.

Lights are difficult to replace

LCD Technologies

TN (Twisted Nematic)

VA (Vertical Alignment)

IPS (In Plain Switching)

TN (Twisted Nematic) LCD

The original LCD technology.

Advantages: Fast response times.

Disadvantages: Poor viewing angles - color shifts.

IPS (In Plain Switching)

Advantages: Excellent color representation.

Disadvantages: Can be more expensive to produce than TN.

VA (Vertical Alignment)

A good compromise between TN and IPS. 

Advantages: Good color representation. 

Disadvantages: Often slower response times than TN.

OLED (Organic Light Emitting Diode)

Organic compound emits light when receiving an electric current. 

No backlight - the organic compound provides the light. 

Lighter and thinner

• Flexible and mobile - no glass needed

Tablets, phones, smart watches. 

• Very accurate color representation.

• Tends to be a bit higher cost than LCD.

Mini LED

Same backlight technology as a conventional LED-backlit LCD.

• But much smaller LEDs.

Each LED can be enabled or disabled.

• And the color and intensity can be different.

Much better control over dark screen areas.

• Deeper blacks, better color representation.

Touchscreen

Merge laptop and tablet input.

• Digitizer responds to touch

• No keyboard required

• But often still available

Many options for input

• Use the best one for the job.

Digitizer

Use a pen-like device as an input.

• Stylus input

• Useful for graphical input

Used commonly on laptop / tablets

• Or hybrid devices. 

Backlight and inverter

LCD displays need a backlight

• Florescent lamp or LED lights

Some laptops have inverters

• Turn DC into AC

Verify backlight

• Look closely 

• Use a flashlight

May need to replace the LCD inverter or display. 

• Choose carefully

Display Attributes

Not all displays are created equal

• Various specifications, options, and settings. 

Requirements can vary.

• Web browsing

• Video and photo editing

• Information displays

• Phones

Evaluate all technical details

• Choose the best display for the requirement.

Pixel Denisty

Measure how many pixels are in an inch.

• Or pixels per centimeter

• Apply a physical measurement to the display. 

A higher pixel density looks better. 

• Higher clarity and sharpness

Consider how the image will be viewed. 

• Displays, printers (dots per inch).

Pixel Density Comparison

Number of pixels / Number of inches

• Pixels per (divided by) inch.

27 inch (diagonal) 4K display

• 3,840 horizontal pixels / 24 inches wide (not diagonal).

• 160 pixels per inch.

65 inch (diagonal) 4K television

• 3,840 horizontal pixels / 57 inches wide.

• 67 pixels per inch.

Refresh Rates

We are viewing many images shown consecutively.

• A still “frame” or image.

Usually measured in hertz (Hz)

• Number of cycles per second - frames per second (FPS)

Frame rates may vary

• Movies: 24 fps

• Television: 30 fps

• Video games: 60 fps and higher

Higher refresh rates are useful for rapidly moving content. 

• Video games, sporting events, video production.

Maximum refresh rate is determined by the video adapter/processor and the display device. 

• The connection between the two is important.

• HDMI 2.1 supports K at 144 Hz

• DisplayPort 2.1 supports dual 4K at 144 Hz

Screen Resolution

The number of pixels - width x height

More pixels means more detailed display output.

• perceived sharpness, a clearer view.

Many standards

• Resolutions can vary widely - 16:9 aspect ratio is common.

Color Gamut

The range of colors available on a display or output device.

This is less than the capabilities of the human eye.

Considerations in a display

Color representation

Range of colors

Standards of color

sRGB: Standard Red Green Blue

Adobe RGB

ITU (International Telecommunication Union) - Standards for HDTV

Color Coverage

A display may be compared with an existing color gamut standard.

• Part of the display specification.

Gamut compatibility can vary.

• High percentages tend to be more expensive.

OLED displays provide a wide color gamut.

• Best-in-class color gamut support.