graphic terminal crt monitor
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A CRT monitor works by using an electron gun to shoot a beam of electrons that hit phosphors on the inside of the screen, causing them to glow. The electron beam is scanned across the screen rapidly through the use of electromagnetic deflection coils, creating a raster pattern to form images. Color CRT monitors use three electron beams and triads of red, green, and blue phosphors to produce a wide range of colors. While CRTs produce high quality images and have good contrast, they are large, heavy, and can pose health risks due to electromagnetic field and x-ray emissions.
graphic terminal crt monitor
- 1. CAD/CAM TOPIC: GRAPHIC TERMINAL (CRT MONITOR) By J KUMAR CHANDRA, ASST. PROF., DEPARTMENT OF ME, NNRG-HYDERABAD
- 2. • Emissive display convert electrical energy into light - Cathode ray tube (CRT) - Plasma panels (gas-discharge display) • Non-Emissive display optical effect: convert sunlight or light fromother source into graphic patterns. - Liquid-crystal device (LCD) – flat panel Displays
- 3. It Consists of.. CRT Anode Cathode Shadow mask Focusing coil Deflecting coil Fluorescent screen
- 5. How It Works? Cathode rays are emitted by an electron gun. accelerated by a high positive voltage near the face of the tube forced into a narrow stream by a focusing system directed toward a point on the screen by the magnetic field generated bythe deflection coils hit onto the phosphor-coated screen phosphor emits visible light, whose intensity depends on the numberof electrons striking on the screen
- 6. How It Works? Electrons travel through a vacuum sealed container from thecathode (negative) to the anode (positive). Because the electrons are negatively charged, they are repelled away from the cathode, and move across the tube to the anode. The ray can be affected by a magnet because of its relation to positiveand negative charges. A CRT monitor contains millions of tiny red, green, and blue phosphor dots that glow when struck by an electron beam. Electron beam travels across the screen to create a visible image. Dot mask ensures proper pixel is lit.
- 7. Phosphore It is a semi-conducteur material which emits visible radiation in response to the impact of electrons. when it absorbs energy from some source such as an electron beam, it releases a portion of this energy in the form oflight. .
- 8. Color Monitors A display monitor capable of displaying manycolors. Color Monitors works like a monochrome one, except that there are three electron beams instead of one. The three guns represent additive colors (red, green and blue) althoughthe beam they emit are colorless. Each pixel includes three phosphors, red, green and blue, arranged ina triangle. When the beam of each of these guns are combined and focused on apixel, the phosphors light up.
- 11. Types of CRT display principles 1. RASTAR SCAN DISPLAY 2. RANDOM SCAN DISPLAY
- 12. CRT Display Principles Electron beam swept across screen one row at a time from top to bottomin raster-scan.
- 13. CRT Display Principles Sample of Random-Scan displays principles. Beam-penetration is used.
- 14. • Phosphor Persistence (PP) - the light output decays exponentially with time. - a phosphor’s persistence is defined as the time from the removal of excitation to the moment of decaying the light to one-tenth of its original intensity • Refresh rate (RR) - number of times per second the image is redrawn. • Resolution - the maximum number of points that can be displayed without overlapon a CRT - high-definition system, e.g. 1280 * 1024 pixels - resolution depends on the type of phosphor, the intensity to be displayed, focusing and deflection systems, size of videomemory Properties of the CRT
- 15. Pros of CRT The cathode rayed tube can easily increase the monitor’s brightnessby reflecting the light. They produce more colours The Cathode Ray Tube monitors have lower price rate than theLCD display or Plasma display. The quality of the image displayed on a Cathode Ray Tube is superiorto the LCD and Plasma monitors. The contrast features of the cathode ray tube monitor areconsidered highly excellent.
- 16. Cons of CRT They have a big back and take up space on desk. The electromagnetic fields emitted by CRT monitors constitute a health hazard to the functioning of living cells. CRTs emit a small amount of X-ray band radiation which can result in a health hazard. Constant refreshing of CRT monitors can result in headache. CRTs operate at very high voltage which can overheat system or result in an implosion. Within a CRT a strong vacuum exists in it and can also result in a implosion They are heavy to pick up and carry around