LED Displays 103: The Physical World

Physical Interactions

Should this be a whole Xxx level?

Mechanical Concerns

Seams

Z-axis Alignment

Curved/Faceted Displays

Viewing Position

Viewing Distance: Fill Factor vs. Pixel Pitch vs. Angular Resolution

Viewing Angle - off axis x/y, impact of z-axis alignment

Viewing Position and Compression Artifacts

Burn-in and Module Replacement

Thermal wear, rework/hot air damage

Colorimetry

White Point

Gamuts

Spectroradiometers

Test Patterns

Thermal Color Shift

Uneven thermal management (heat sink) can cause a spatial artifact, typically a pink/green or pink/cyan shift in a donut pattern around the module. Also shows PSU thermals if PSU is closely coupled or acts as an insulator to LDM.

LED on Camera

Timing: Frame Rate, Phase Offset, Refresh Rate, Shutter Angle, Multiplex Patterns

How to determine an LED display single refresh time

  • Set shutter speed as fast as possible until the dark part of the image is actually black
  • Increase shutter speed until the black lines disappear
  • The current shutter speed is the base time of an LED image refresh. Multiples of this shutter speed will be additional speeds that will create a smooth image without scan artifacts

Global & Rolling Shutter

Gamma, OETF/EOTF, OOTF

Genlock, Frame Lock, Frame Rate Conversion: When Do We Actually Need Genlock

Moire & Spatial Aliasing

Multiplexing

Brightness, bit depth decimation