OUTPUT DEVICE An output device is a piece of hardware that is used to display or output data which has been processed or has been stored on the computer.
Speakers Most computers are fitted with a small internal speaker which can produce beeping sounds to alert you if you make an error. Computers can also be fitted with a sound card (or chip) which will enable sound to be output through external speakers. These usually produce a much higher quality sound than the internal speaker. Speakers convert electrical signals into sound waves. Loudspeakers are essential for applications such as music editing, video conferencing, watching movies, etc. Advantages Everyone in the room can hear the output from the computer. They can help create an atmosphere or ambiance to accompany a presentation. They help blind people to use the computer because text can be converted into sound. Disadvantages The output from speakers can disturb others who are trying to work. High quality external speakers can be expensive.
Headphones Headphones and earphones consist of a pair of small loudspeakers which are worn over or in the ears. They are connected either by cable or wirelessly to a device such as a computer, radio or MP3 player. A transducer converts the electronic signals from the device into sounds which can then be heard by the user via the earphones. Advantages • The sound can only be heard by the user (mostly). • Portability - lightweight and easy to carry around. • Can listen to music on the move. • Although prices vary, many headphones and earphones are inexpensive. Disadvantages • If music is played too loudly or for long periods of time there is a risk of permanent hearing loss. • Often not aware of surrounding noises such as cars in traffic or people talking. • If the music is too loud or the headphones not fitted correctly then others can hear an annoying sound from them. • Can be uncomfortable to wear for long periods of time. • If the device is large e.g. a computer, it is not easy to move about the room while wearing the headphones
Plotter Plotters are a specialist type of printer which is able to draw high quality images on very large piece of paper. They are used by engineers, architects and map-makers to draw plans of buildings, diagrams of machines or large scale maps. They can also be used for many other similar tasks. A plotter differs from a printer in that it draws images using a pen that can be lowered, raised and moved across the paper to form continuous lines. The electronically controlled pen is moved around the paper by computer controlled motors. There are two different types of plotter: Flatbed plotters - A graphics plotter that contains a flat surface that the paper is placed on. and pens are moved to draw the image. The size of this surface (bed) determines the maximum size of the drawing. Drum plotters - In drum plotters the pen is moved in a single axis track and the paper itself moves on a cylindrical drum to add the other axis or dimension. Drum plotter is used to produce continuous output, such as plotting earthquake activity or for long graphics output such as structural view of a skyscraper.
Advantages: • They can produce huge printouts. • The print quality is extremely high. Disadvantages: • They are very expensive to buy and maintain. Their print times are very slow.
Printers Printers is an output device that produces text and graphics on paper. Many printers are primarily used as local peripherals and are attached by a printer cable or in newer printers a USB cable to a computer which serves as a document source. In addition , a few modern printers can directly interface to electronic media such as memory card, or to image capture devices such as digital camera.
Factors affecting print quality DPI: It is a measurement of printer’s resolution indicating how many ink dots can be placed by the printer in one square inch. The higher the DPI, the sharper is image. Type of printer: Each type of printer has its own capabilities of printing. Some types of printers produce high quality print while other produce low quality print. Print Mode: The printing mode may also affect the quality. For example the draft mode increases the print rate but quality is reduced. Toner: The quality and amount of toner also affects print quality.
Types of Printers Printers Impact Printers Non-Impact Printers Inkjet Thermal Laser Daisy wheel Dot- Matrix
Impact Printer These printers have a mechanism that touches the paper to create an image. These printers work by banging a print head containing a number of metal pins which strike an inked ribbon placed between the print head and the paper.
Non-Impact Printers These printers create an image on the print medium without the use of force. They don’t touch the paper while creating an image. Non-impact printers are much quieter than impact printers as they don’t strike the paper.
“Dot Matrix Printer” • The term dot matrix refers to the process of placing dots to form an image. • Its speed is usually 30 to 550 characters per second (cps). • This is the cheapest and the most noisy printer and has a low print quality. Dot Matrix were 1st introduced by Centronics in 1970.
How Dot-Matrix works? • The dot matrix forms images one character at a time as the print head moves across the paper. • Uses tiny pins to hit an ink ribbon and the paper much as a typewriter does. • This printer arranges dots to form characters and all kinds of images. • 9 to 24 vertical column pins are contained in a rectangular print head. When print head moves across the paper, pins are activated to form a dotted character image. These printers can produce carbon copies along with the originals.
Advantages/Dis-advantages of Dot-Matrix Advantages: (1) In-expensive. (2) Low per page cost. (3) Energy efficient. Dis-advantages: (1) Noisy (2) Low resolution (3) Limited fonts flexibility (4) Poor quality graphics output.
Ink-Jet Printer It is a non-impact printer producing a high quality print. A standard Inkjet printer has a resolution of 300dots per inch. Newer models have further improved dpi. Inkjet printers were introduced in the later half of 1980s and are very popular owing to their extra-ordinary performance.
How Inkjet Printer works? (1) Print head having four ink cartridges moves . (2) Software instructs where to apply dots of ink, which color and what quantity to use. (3) Electrical pulses are sent to the resistors behind each nozzle. (4) Vapor bubbles of ink are formed by resistors and the ink is forced to the paper through nozzles. (5) A matrix of dots forms characters and pictures.
Advantages/ Dis-advantages Advantage: • Cheap to buy - cheaper than a laser printer • More compact than a laser printer • Cartridges cost less to replace than toners • Produce good quality printouts better than a dot-matrix but not as good as a laser • Speed - faster than a dot-matrix but not as fast as a laser Disadvantage: • Noisier than a laser printer (but not as noisy as a dot-matrix) • Color printing can be extremely slow • Cost of printouts per page are more expensive than a laser printer • Cartridges need to be replaced more often than a laser printer • Ink will smudge while it is still wet • Colors can become saturated and often don't look the same as on the screen. • If not used for a while, the cartridges can dry out
Laser printer • Laser printers are non-impact printers which can print text and images in high speed and high quality resolution, ranging from 600 to 1200 dpi. • Color laser printers offer good quality for work such as flyers or other commercial material. How Laser printer Works? (1) Paper is fed and the drum rotates. (2) A laser beam conveys information from the computer to a rotating mirror and thus an image is created on the drum. (3)The charges on the drum are ionized and the toner sticks to the drum. (4)Toner is transferred from drum to paper. (5)Heat is applied to fuse the toner on the paper.
Advantages $ Disadvantages of Laser printer Advantages: High quality printouts - better than ink-jet or dot-matrix Fast printouts - faster than ink-jet or dot-matrix Prints very quietly - quieter than ink-jet or dot-matrix Cost per page is low - cheaper than ink-jet or dot-matrix Disadvantages: Most expensive printer type to buy, especially colour lasers Toner is more expensive than ink-jet cartridges Expensive to repair - lots of complex equipment inside Fairly bulky - larger than ink-jet printers Can't use continuous or multi-part stationary to create carbon copies like you can with a dot-matrix printer
Printers for different users • To choose a printer from a printer’s family following considerations are to be made. • (1) What’s the budget? • (2) Is color needed or just black& white? • (3) What is the Volume of the output? • (4) How important is the quality of the output? • (5) What special features are needed? • (6) Is the printer is to be used by a single user or a whole network?
Actuator Anactuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion. An actuator is the mechanism by which a control systems acts upon an environment. The control system can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), or a human or other agent
LCD , LED Masooma Malik
INTRODUCTION Television(TV) is a telecommunication medium for transmitting and receiving moving images that can be monochrome (Black and White) or colored, with or without accompanying sound. The word Tele is a Greek word meaning “Distant” and Vision meaning “Sight”. The components used in old TV's are essentially very similar to the components used in modern TV's; that is, they perform the same function as their modern counterparts. Where they differ greatly however, is in their size.
There are different types of TV depending upon the display device used. • Display Device A display device is an output device for presentation of information in visual form. When the input information is supplied as an electrical signal, the display is called an electronic display. • Types of Display Devices • Cathode Ray Tube • Flat - Panel Display
CATHODE RAY TUBE 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.
FLAT PANEL DISPLAY Flat panel displays (sometimes referred to as flatscreens, which more technically mean screens with fully flat front surfaces) encompass a growing number of electronic visual display technologies. They are far lighter and thinner than traditional television sets and video displays that use cathode ray tubes (CRTs), and are usually less than 10 centimetres (3.9 in) thick.
LIQUID CRYSTAL DISPLAY(LCD) Liquid-crystal display televisions (LCD TV) are color television sets that use LCD technology to produce images Produces colored image by selecting filtering a white light Thinner and lighter than CRTs of similar display size The concept of LCD was 1st brought up by Philips
LIQUID CRYSTAL DISPLAY ISOTROPIC ANISOTROPIC (Liquids and gases) (Liquid Crystals have orientational order) Liquid Crystal – a stable phase of matter characterized by anisotropic properties without the existence of a 3-dimensional crystal lattice – generally lying between the solid and isotropic (“liquid”) phase.
Unique Properties of Liquid Crystals The orientation of Liquid Crystals can be affected by… • Pressure • Temperature • Electrical Field
LCD Preparation Checking the ITO Glass Rubbing the PVA to create an alignment layer Removing the PVA at one edge Placing the Saran Wrap Spacers Applying the Liquid Crystal Placing the Polarizers at 90°
PROPERTIES OF LCD DISPLAY • Light weight (typ. 1/5 of CRT) • power consumption (typ. 1/4 of CRT) • No electromagnetic emission • Large screens (>20 inch) on desktops • Completely flat screen - no geometrical errors • Crisp pictures - digital and uniform colors • Fully digital signal processing possible • Low luminance (typ. 200 cd/m2)
Led • An LED-backlit LCD display is a flat panel display that uses LEDbacklighting instead of the cold cathode (CCFL) backlighting used in other LCD displays. • While not an LED display, televisions using this display are called "LED TV" by some manufacturers and suppliers. • The use of LED backlighting allows for a thinner panel, lower power consumption, better heat dissipation, a brighter display, and better contrast levels • Three forms of LED may be used: • White edge-LEDs around the rim of the screen, using a special diffusion panel to spread the light evenly behind the screen (the most usual form) • A full array of LEDs arranged behind the screen whose brightness are not controlled individually
Where are they used? Light-emitting diodes are used in applications as diverse as aviation lighting, automotive lighting, advertising, general lighting, and traffic signals. LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players and other domestic appliances.
Difference between LCD and LED • Produce images with greater dynamic contrast; • With edge-LED lighting can be extremely slim, some screens less than half an inch (0.92 cm) thick. • Offer a wider color gamut when RGB-LED backlighting is used. • Produce less environmental pollution on disposal; • Are more expensive; • Have typically 20 to 30% lower power consumption; • Are more reliable. • Can allow a wider dimming range.
LCD Projector Vs DLP Projector Masooma Malik
Multimedia Projectors Multimedia Projector Remote control • These receive signals from Computers, Televisions and DVD Players and project the image onto a large screen. • Multimedia Projectors are usually controlled using a Remote Control. • The remote control makes it possible to direct the presentations without the need to be at the computer.
Uses: Can be used for training presentations to allow the whole audience to see images from a computer. Can also be used for large scale advertising of new products – Home cinema systems where images from DVD‟s or Televisions are projected to a large screen.
Advantages: Enable many people to clearly view a presentation. Enhance the viewers experience. For example – watching movies on a large screen is better than a small TV screen. Disadvantages: Very expensive to buy. Can be difficult to set up. Images can sometime be fuzzy.
LCD Projector It start with a source of light (lamp) and split the light into three beams. Each beam passes through its own LCD panel. The LCD panels each have hundreds of thousands of tiny pixels, the higher the resolution, the more pixels. Data determines whether light is allowed to pass through each one. One of three LCD panel has a red filter, one a green, and one a blue filter. The light is then recombined, using a dichroic prism. The combined, now in full color, passes through the lens and hits your screen.
Advantages Disadvantages Richer color dynamics for better results in rooms with ample ambient light . Draw less power. Throw less heat. No color filter wheel = No "rainbow effect" Slightly quieter. Seemingly sharper image on data. More visible pixels. Some screen door effect on certain video images. Physically larger - Even for the same number of lumens. Poorer contrast. Blacks come out lighter gray than DLP projectors.
DLP Projector DLP projectors were developed by Texas Instruments and project images by reflecting lights against hundreds of tiny mirrors called digital micro devices (DMD). A color, spinning wheel (referred to as a color wheel), combined with timing, allows the light to come out the correct colors, and pass through the lens on its way to the screen. DLP projectors are lighter in weight than their LCD counterparts. DLP have higher contrast ratios, meaning that they project video images better than LCDs. They are portable, tend to be smaller and lighter than LCDs and connect easily to other digital devices.
Advantages Disadvantages Smoother video. Smaller box. Pixels far less visible, (although normally not an issue for business use). More “film like” on DVD and HDTV. Generate "blacker" blacks. Rainbow effect bothers some. More moving parts (color filter wheel). Color filter wheel often produces soft but audible whine. Poorer reds and yellows at full power. Color saturation. Need more lumens than LCD, for rich colors, when dealing with ambient light.