Final Visual Display Unit Presentation 2007 main

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Warm “WELCOME” To All o f You Present Here

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VISUAL DISPLAY UNIT

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What is Visual Display Unit ? Computing a device with a screen that displays characters or graphics representing data in a computer memory. It usually has a keyboard or light pen for the input of information or inquiries A VDU displays images generated by a computer or other electronic device. The term VDU is often used synonymously with "monitor," but it can also refer to another type of display, such as a digital projector. Visual display units may be peripheral devices or may be integrated with the other components. For example, the Apple iMac uses an all-in-one design, in which the screen and computer are built into a single unit.

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Types of Visual Display Unit Mainly there are 4 types of VDU’s as follows :- ( CRT) Cathode Ray Tube – 1897 – Ferdinand Braun Plasma – 1964 – Donald Bitzer and Gene Slottow (LCD) Liquid Crystal Display – 1888 – Friedrich Reinitzer discovers the liquid crystalline nature of cholesterol extracted from carrots. In 1996 it came into existence by Samsung. (LED) Light Emitting Diode – 1927 – Oleg Vladimirovich Losev

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CRT in detail The Cathode Ray Tube ( CRT ) is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen. As a matter of safety, the face is typically made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions. Color and monochrome CRTs may contain toxic substances, such as cadmium, in the phosphors. The rear glass tube of modern CRTs may be made from leaded glass, which represents an environmental hazard if disposed of improperly.

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1. Three Electron guns (for red, green, and blue phosphor dots). 2. Electron beams. 3. Focusing coils. 4. Deflection coils. 5. Anode connection. 6. Mask for separating beams for red, green, and blue part of displayed image . 7. Phosphor layer with red, green, and blue zones. 8. Close-up of the phosphor-coated inner side of the screen. Structure of CRT monitor :-

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Advantages :- High dynamic range (up to around 15,000:1), excellent color, wide gamut and low black level. The color range of CRTs is unmatched by any display type except OLED. Can display in almost any resolution and refresh rate Sub-millisecond response times Excellent viewing angle. Allows the use of light guns/pens. Disadvantages :- High power consumption. On average, LCD monitors consume 50-70% less energy than CRT monitors. Generates a considerable amount of heat when running Produces noticeable flicker at low refresh rates CRTs give off electric, magnetic and electromagnetic fields. There is considerable controversy as to whether any of these pose a health hazard. They are large, heavy, and bulky.

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PLASMA in detail A plasma display panel (PDP) is a type of flat panel display. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps. It works with two types of gases namely Xenon & Neon sandwiched between 2 glass plates.

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Structure of PLASMA monitor :-

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A plasma display panel is an array of hundreds of thousands of small, luminous cells positioned between two plates of glass. Each cell is essentially a tiny neon lamp filled with rarefied neon, xenon, and other inert gases; the cells are luminous when they are electrified through "electrodes" Ionized gases such as the ones shown here are confined to millions of tiny individual cells across the face of a plasma display, to collectively form a visual image.

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Advantages :- Capable of producing deeper blacks allowing for superior contrast ratio Wider viewing angles than those of LCD. Less visible motion blurs. have lifespan exceeding 100,000 hours, far longer than older CRT technology Disadvantages :- Use more electricity, on average, than an LCD TV. Do not work as well at high altitudes due to pressure differential between the gases inside the screen and the air pressure at altitude. They are large, heavy, and bulky.

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LCD in detail A Liquid Crystal Display ( LCD ) is a flat panel display that uses the light modulating properties of liquid crystals which do not emit light directly. They are used in a wide range of applications, including computer monitors, television, instrument panels, aircraft cockpit displays, signage, etc. Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, and two polarizing filters, perpendicular to each other. With no actual liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second.

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Structure of LCD monitor :-

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LCD is made of a cell that contains liquid crystal material sandwiched between two glass plates. Lines and columns of the transparent conductor are configured on the inner surfaces of the cell. A transparent polarizing film is attached to the top glass plate. Pre-tilted angle is to twist LC for the direction. A Color Filter Glass has color filter which generates color. Liquid crystals move according to the difference in voltage between the Color Filter Glass and the TFT Glass. The amount of light supplied by Back Light is determined by the amount of movement of the liquid crystals in such a way as to generate color.

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Advantages :- Very compact and light. Low power consumption. Little or no flicker depending on backlight technology. Can be made in almost any size or shape. Comparatively light in weight. Disadvantages :- Limited viewing angle, causing color, saturation, contrast and brightness to vary. Not all LCD’s are designed to allow easy replacement of the backlight. Cannot be used with light guns/pens. Loss of contrast in high temperature environments. Many cheaper LCD’s are only able to display 262,000 colors. 8-bit IPS panels can display 16 million colors and have significantly better black level, but are expensive.

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LED in detail A Light Emitting Diode ( LED ) is a semiconductor light source. LED’s are used as indicator lamps in many devices and are increasingly used for other lighting. When a light-emitting diode is forward biased (switched on), electrons are able to recombine with electron within the device, releasing energy in the form of photons. This effect is called electroluminescence. LED is powerful enough for room lighting and are relatively expensive, require more precise current and management than compact fluorescent lamp sources of comparable output.

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Structure of LED monitor :- Although not directly labeled, the flat bottom surfaces of the anvil and post embedded inside the epoxy act as anchors, to prevent the conductors from being forcefully pulled out from mechanical strain or vibration.

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Advantages :- LEDs emit more light per watt than incandescent light bulbs. Their efficiency is not affected by shape and size, unlike fluorescent light bulbs or tubes. LEDs light up very quickly. A typical red indicator LED will achieve full brightness in under a microsecond. LEDs can very easily be dimmed by lowering the forward current. LEDs can have a relatively long useful life. One report estimates 35,000 to 50,000 hours of useful life. LEDs, being solid state components, are difficult to damage with external shock and are light in weight. Disadvantages :- LEDs are currently more expensive. Adequate heat sinking is needed to maintain long life. LED TV do not have better Contrast ratio.

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CRT LED LCD PLASMA

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Thank You Guidance Under Hardik Sir Nirav Sir

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Abridged & Presentation By Sandip V. Kalola Akshay M. Hirani Ashwin G. Sutariya Jay D. Vaghela