Display Panel Technologies
LCD (Liquid Crystal Display): the most common display technology. Liquid crystals control light polarization; a backlight provides illumination. LCD subtypes: TN (Twisted Nematic) — fast response times, lower color accuracy, narrow viewing angles; best for gaming. IPS (In-Plane Switching) — better color accuracy, wider viewing angles, slight response time penalty; best for photo/video editing and general use. VA (Vertical Alignment) — best contrast ratio (true blacks), moderate response time and viewing angle; good all-rounder.
OLED (Organic Light-Emitting Diode): each pixel emits its own light — no backlight needed. Results in: perfect blacks (pixel turns completely off), infinite contrast ratio, wide viewing angles, thinner panels. Disadvantage: burn-in risk (static elements displayed for hours/days can permanently damage pixels), typically more expensive. Common in smartphones, high-end monitors, and OLED TVs. AMOLED: Active Matrix OLED — used in smartphones (Samsung Galaxy).
Resolution: number of pixels. Standard definitions: 1080p (1920×1080 — Full HD, FHD), 1440p (2560×1440 — Quad HD, QHD), 4K (3840×2160 — UHD). Higher resolution requires more GPU power. DPI (dots per inch): pixel density — higher DPI = sharper image at same display size. 27-inch at 1080p appears blurrier than 27-inch at 1440p because pixel density is lower.
Refresh rate: how many times per second the display updates — measured in Hz. 60 Hz: standard. 120/144 Hz: gaming — noticeably smoother motion. 240/360 Hz: competitive gaming. Higher refresh rate = smoother but requires GPU to output enough frames. Response time: how quickly a pixel changes color — measured in ms. Lower is better for gaming (1ms GTG vs 5ms). Slow response time causes 'ghosting' — blurry trails on moving objects.
Display Connections and Troubleshooting
Video output connectors: HDMI — most common, carries audio and video, supports 4K@60Hz (HDMI 2.0) or 4K@120Hz and 8K (HDMI 2.1). DisplayPort — higher bandwidth than HDMI, supports 4K@144Hz and 8K (DP 1.4), daisy-chaining multiple monitors. USB-C/Thunderbolt — carries video (DisplayPort or Thunderbolt protocol) via USB-C connector, supports power delivery. VGA (15-pin D-sub) — analog, legacy — still found on projectors and older monitors, no HDMI audio. DVI — digital (DVI-D) or combined analog/digital (DVI-I), legacy.
Display troubleshooting: no image — verify cable connections, try different cable, try different port on GPU, test monitor with another source. Flickering — check for loose cable, damaged cable, incompatible refresh rate settings. Dim display — check brightness settings, may indicate failing backlight (CCFL in older LCDs). Vertical lines — often GPU or cable failure. Dead pixels: permanently on (stuck, a color) or permanently off (black). Burn-in: ghost image of previous static content — OLED and older plasma risk. Physical damage to LCD panel: bright spots, dark spots, cracks — requires panel replacement.
Projectors: use in conference rooms and classrooms. Connection: HDMI or DisplayPort from laptop. Lumens: brightness rating — 2000+ lumens for bright rooms. Types: DLP (Digital Light Processing, uses rotating color wheel), LCD (three separate LCD panels for RGB). Keystone correction: adjusts for angled projection to make image rectangular. Focus ring: manual focus adjustment.