Crt - cathode ray tube, Computer Graphics

Assignment Help:

CRT - Cathode Ray Tube

  • Electron gun is used to send an electron beam aimed at a particular point on the screen. Deflection system is used to make the beam strike the screen on a precise point.
  • When electron beam strikes the screen, coated phosphor emits light due to the natural phenomenon called phosphorescence. Output decays rapidly approximately within 10 - to 60 microseconds.
  • As a result of this decay, the entire screen must be refreshed at least 30-60 times per second. This is called the refresh rate. If the refresh rate is low, screen will tend to flicker.
  • CFF (Critical Fusion Frequency) is the minimum refresh rate needed to avoid flicker. It depends on the persistence of the phosphors and the human vision system.
  • Electron beam traces out a path on the screen, hitting each pixel once per cycle. Tracing out of the entire picture once is called a cycle. In case of a raster scan display we call the horizontal path of the beam a scan line. In case of random scan display, the path is a directed set of line segment, which are called vector lines.
  • On a raster scan display, refresh rate is fixed as mentioned above. On a vector display, a scan is in the form of a list of directed line segments to be drawn, so the time to refresh is dependent on the length of the display list. For small and simple object displays, some kind of delay is introduced to avoid un-necessary refreshing of the screen.
  • In color CRT, shadow-mask method is most common since it produces a wide range of colors. In this method, each pixel consists of a group of three phosphor dots (one each for red, green, and blue), arranged in a triangular form called a triad. The shadow mask is a grid structure with one hole per pixel. To excite one pixel, three electron guns are used one for each of red, green, and blue. Each gun fires its electron stream through the hole in the mask to hit that pixel.

Related Discussions:- Crt - cathode ray tube

Differentiate images and graphics, Question 1 Discuss the general properti...

Question 1 Discuss the general properties of analog signal Question 2 Differentiate images and graphics Question 3 Explain the video compression standard H.263

2d clipping algorithms - clipping and 3d primitives, 2D Clipping Algorithms...

2D Clipping Algorithms Clipping is an operation that eliminates invisible objects from the view window.  To understand clipping, recall that when we take a snapshot of a scene,

Languge, what languge do computers speak

what languge do computers speak

Differentiate between a raster image and vector image, Question: (a) D...

Question: (a) Describe in details the meaning of the following terms often available in drawing tools: (i) Welding objects; (ii) Trimming objects; (iii) Intersecting obje

Convex shaped window and concave or non convex shaped window, Well you migh...

Well you might surprise to what a convex window? In common, on the basis of the shapes the windows are categorized into two classes: i) A Convex shaped windows: Windows of a s

What is aspect ratio, Define  Aspect ratio- Aspect ratio: The ratio ...

Define  Aspect ratio- Aspect ratio: The ratio of vertical points to horizontal points necessary to produce equal –length lines in both directions on the screen, is called as

Advantages and deficiencies of gourand shading, Advantages and Deficiencies...

Advantages and Deficiencies of Gourand Shading Advantages of Gourand Shading: this eliminates the intensity discontinuities related with the constant shading model. Defi

Mapping of a fraction -windowing transformations, Mapping of a Fraction -Wi...

Mapping of a Fraction -Windowing Transformations The mapping of a fraction of a world coordinate scene to device coordinates is considered to as Viewing Transformation. In com

Liang barsky line clipping algorithm, Liang Barsky line clipping algorithm ...

Liang Barsky line clipping algorithm : The algorithm uses parametric form of the line segment.  Four inequalities are created using the parametric form of the line segments.  Th

Traditional animation techniques , Traditional Animation techniques as: ...

Traditional Animation techniques as: 1) Key Frames                        2) Cel Animation Formula: Required Key frames for a film = {[Time(in seconds)]

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd