---
title: "Short note: Plasma display"
subject: "Computer Graphics"
chapter: 1
key: "semester_5/computer_graphics:short-note-plasma-display"
source: https://www.bctengineer.com/q/semester_5/computer_graphics/short-note-plasma-display
site: BCT Engineering
---

# Short note: Plasma display

Computer Graphics · Chapter 1: Introduction and Application

- Asked in: 2068 Bhadra (old course), 5 marks
- Video: [Plasma panel display in computer graphics](https://www.youtube.com/watch?v=8xlh6bHyoUA) — Sandeep Kumar Gour
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/computer_graphics/short-note-plasma-display
- Whole chapter: https://www.bctengineer.com/md/semester_5/computer_graphics/chapter-1

## Question

Write a short note on plasma display.

## Short answer

A plasma display uses tiny gas-filled cells between two glass plates with electrode grids. Applying voltage ionizes the gas, emitting UV that excites red, green, or blue phosphors. It provides wide viewing angles and large screens, but consumes more power and risks burn-in.

## Answer

A **plasma display** is an emissive flat panel display in which each pixel is a tiny cell filled with an inert gas (neon-xenon mixture) that glows when voltage is applied.

```text
 Glass plate  with vertical conducting ribbons
     |  gas cells (pixels) at the crossings
 Glass plate  with horizontal conducting ribbons
```

**Working**
1. A grid of vertical conductors is on one glass plate and horizontal conductors on the other; the gas lies between them.
2. To light a pixel, a firing voltage is applied to the horizontal and vertical lines crossing at that point. The gas ionises into plasma and emits ultraviolet light.
3. The UV light excites a red, green or blue phosphor in the cell, which gives visible light.
4. A lower sustaining voltage keeps the cell glowing; the pixel is turned off by lowering the voltage. Refreshing keeps the picture.

**Advantages:** large screens, wide viewing angle, good contrast and brightness, no flicker, thin.
**Disadvantages:** high power use, heating, costly, risk of screen burn-in, lower resolution than LCD.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What fills a plasma display's cells?
   A. Liquid crystal
   B. Phosphor powder only
   C. Neon-xenon inert gas
   D. Organic layers
   Answer: C. Gas cells are pixels. (Key point: Gas)

2. How is a pixel lit?
   A. A beam hits phosphor
   B. Backlight passes polarizers
   C. LED turns on
   D. Firing voltage on the crossing horizontal and vertical lines ionises gas to emit UV
   Answer: D. Plasma emits UV, which excites phosphor. (Key point: Lighting a pixel)

3. How does the display produce visible colour?
   A. UV excites red, green or blue phosphor
   B. Gas emits colour directly
   C. Filter on backlight
   D. Polarizer
   Answer: A. Phosphor converts UV into visible light. (Key point: Colour)

4. How is a cell kept glowing?
   A. Constant firing voltage
   B. A lower sustaining voltage
   C. Backlight
   D. Cooling
   Answer: B. Sustaining voltage maintains the glow. (Key point: Keeping lit)

5. Which is a disadvantage of plasma?
   A. Narrow viewing angle
   B. Flicker
   C. High power use and burn-in risk
   D. Thick panel
   Answer: C. Listed drawbacks include power, heat, burn-in. (Key point: Disadvantage)