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Input Devices

Physical devices, input devices using light and other input devices.

Holly E

on 24 January 2013

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Transcript of Input Devices

Infra-red remote control LEARN WELL! The Input Device Room! Here to answer all your questions
on input devices! I hope you have enjoyed the presentation! Make sure you learn all those bullet points as they are the key facts! Good luck! MICROPHONE (SPEECH OR VOICE) - Speech or voice input - rapidly developing
means of input
- Important method for handicapped people, or when the users hand have to be free for use elsewhere -
still mainly restricted to these ares
- Programs available which recognise
continuous speech input (translate words
directly into a word processor)
- Some words sound the same but used in
different contexts (weather + whether)
(sale + sail)
- These programs can select the
appropriate `spelling from the
sentence being spoken SCANNER Used to input pictures and text into a computer
Requires special software (OCR) - Used on bank cheques
- Important data printed on a bank cheque
along bottom edge as strange-looking characters
- These are required for processing
- Ink used contains tiny magnetic particles (enables data to be read into the computer)
- Fast, reliable method as it is unaffected by scribbling over characters with a pen) QWERTY Keyboard (called this as the first letters are the top 6 keys)
Basic layout is similar in many countries
Some designed with a curved (ergonomic) key layout to make typing faster and comfortable

Disadv. Relatively slow compared to other input devices, even for touch-typists There are different types of mice: Mouse
Movement is mirrored by the pointer on the monitor screen
Some still have a ball underneath, but most are optical, use a light beam and detector
How? It shines a beam of light onto the surface and due to the reflection, movement is detected
A mouse can be clicked, double clicked or dragged to activate a process
Most have a small wheel too - use depends on the software e.g. scroll up or down or zoom
Many use infra-red or wireless links so there is no need for a connecting cable Welcome to today's class! Good luck! MAGNETIC STRIPE - Thin strips of magnetic tape on back of many types of plastic card eg. debit and credit cards, library cards, cinema and train tickets
- When card is used by reader, stripe passes playback heads (similar to a tape recorder) which reads data from stripe
- Cards with stripes used for eg. keep track of supermarket loyalty schemes Today we will be discussing
-Physical input devices
-Input devices using light
-Other input devices LET'S BEGIN! Input devices
used for control Some computers are used to
monitor the environment or control machines

Sensors turn physical parameters into digital signals suitable for a computer LIGHT Used to sense daylight for greenhouses or streetlights

Light beams and infra-red movement can help burglar detection

Video cameras for capturing an image Position Used to sense the position of wind vanes and operator switches

Detect vibration (e.g. for car alarms)

Used in robotics and global positioning systems (GPS) for navigation Temperature To monitor weather forecasting
Control washing machine water heating
Open greenhouse windows
Operate central heating
Used in scientific experiments
Fire detection Pressure Sense body weight in a burglar alarm system

Sense air pressure in weather forecasting

Sense water depth and pressure in washing machines

Sense traffic passing along the road (traffic monitoring system) KEYBOARDS There are different types of keyboards Braille Keyboard (used my the visually impaired)
Letters and symbols read by fingers moving across a series of dots
Can be plugged directly into a computer
Overlays can be placed over the keys of a QWERTY keyboard There are no disadvantages to this, but you do have to be able to read braille to use this keyboard. Concept Keyboard (flat panel of contact switches covered by a flexible membrane)
Each switch can be programmed to respond in different ways
Overlays with pictures and/or symbols are placed over the membrane
Popular in primary schools
Used in restaurants to speed up entries
Some supermarkets for fruit and vegetables
Found in environments where the keyboard could be damaged (membrane protects it) THE MOUSE Trackerball
Similar to a mouse but ball is set into a cup on the top of the unit
Use a finger or on bigger trackerballs, the palm of the hand, to roll the ball in any direction
It is useful for people with limited motor skills
Ball controls movement of pointer on screen
Buttons on a trackerball work the same as a mouse Joystick Popular for computer games
Can be moved around the central axis in any direction
Spring-loaded to the centre
Have many more buttons
Some have 'force feedback' (able to feel forces that may have been experienced in real life) TOUCH PAD Found on laptops and offer the same functions as a mouse
Moving fingers across controls movement of pointer
Tapping lightly = click
Also has switches for left and right mouse buttons Graphics tablet Flat pad user can write or draw on using a stylus
Surface of the pad is sensitive to the pressure of the stylus
As the stylus is moved across the pad, the movement is translated to a drawing on the computer monitor
Harder the stylus is pressed, the thicker the line on the screen
Typical resolution = 1/1000 cm HOW DOES IT WORK? Place picture face down on glass
Bright light is slowly moved across
Reflected light is focused onto a light-sensitive device using several mirrors and a lens
White parts reflect most light, black the least
Colours reflect different wavelengths of light
Each part of picture is converted into a digital signal
Scanned work is usually used in publishing work OPTICAL MARK READER (OMR) Detect marks made on paper
Usually recommended that the marks are soft (HB) pencil and black pen
Reader scans across the paper
with an infra-red light
No mark = strong reflection off the white paper
Where there is a mark, light reflection is reduced
This is to input to the computer
Used for lottery tickets, recording answers on multiple choice papers, school registers, recording gas and electricity metre readings Picture taken is stored in computer memory rather than on film
Different colours are converted to digital signals (codes of 1 and 0) by sensors behind the lens
Pictures can be: displayed on monitor, imported into graphics7art program for editing, printed
Quality = determined on resolution of the camera (measured in pixels)
High quality cameras = 10 or more megapixel resolution
Most cameras have liquid crystal display (LCD) screen - displays picture taken
User can view or discard photo
The cost is much less than a traditional camera as film and processing don't have to be purchased
High quality paper and an ink jet printer are required for printing digital pictures CAMERAS OPTICAL CHARACTER RECOGNITION (OCR) Used to recognise letters, numbers and words
Clearer the writing, the more accurate the scan
Software improved to read different styles and sizes of type and neat handwriting
One application is reading postcodes/ZIP codes on letters at sorting offices (letters can then be sorted automatically)
Another use is passport control - biometric passports have 2 lines of text that can be read by the machine Digital Camera Web Cam A digital camera that sits on or by a computer
Digital images input directly to the computer (can be used for video conferencing with other users over the network)
Tend to be of lower resolution and poorer quality than expensive digital cameras Video Capture Digital camcorders can plug straight into computers through a Firewire connection (very fast data link to computer)
This allows the computer to download, store and manipulate digital video images
Older analogue camcorders can also connect to a computer but need a video digitiser card fitted in the computer
Video capture and editing take up a lot of space on computer memory so the computer needs large hard disk drives
Special software can compress files to 1/100th of original size with little quality loss Digital camera in mobile phones can be used to take still images and short videos - IR used to change channels and volume on a television or hi-fi
- Button pressed - series of light pulses emitted by LED on the front of the remote
- LED = Light-emitting diode
- Beams picked up by an infra-red receiver
- Embedded microprocessor interprets the signal and carries out required action
LIMITATIONS: line of sight, can't travel +10m, can use radio signal TOUCH SCREEN - On screens - criss-cross beams of IR light in front glass of monitor
- When user touches glass - 2 sets of rays are blocked (side to side, top to bottom)
- Computer detects fingers position from light sensors (opposite side of monitor screen to the light sources)
- User friendly
- Input devices for information systems in public places eg. museums, airports, tourist offices THINGS TO REMEMBER! BAR CODE READER - Pattern of black/white bars or dots
- Scans bar code - translates it into data that can be processed by a computer
- Sends a beam of light (laser)
- Black bars/dots absorb light
- White bars/dots reflect light
- Decodes these signals, converts to text, passes data to computer, processes code
- Fast, reliable method of entering data
- Surfaces can be curved or upside down
- Hand held or fixed lasers or pen-like devices (wand bar code readers) LIGHT PEN - Pen shaped device connected to a computer
by a cable
- Used with a CRT monitor (cathode ray tube)
- Doesn't emit light - but has a light detector
in tip of pen (picks up light signals from
- Pen can be made to work like a mouse
(selecting menus, activating programs,
drawing lines on screen)
- Not common input device - but is used in art and design work MAGNETIC INK CHARACTER
RECOGNITION (MICR) SMART CARD - smart card (ICC - integrated chip card) is a plastic card containing a microprocessor chip
- Enables more data to be stored and the PIN (personal identification number) entered by user to be checked against info in the chip
- PIN entered using a numeric keypad - Data on smart cards more secure on
cards with magnetic stripes
- Have been widely adopted by banks through
the CHIP and PIN system
Smart cards also used for mobiles and satellite
television receivers. MUSICAL INSTRUMENT DIGITAL INTERFACE (MIDI) - MIDI developed as standard for linking keyboards and instruments together
- Computers fitted with MIDI interface boards can be connected to MIDI instruments allowing music to be input and output to a computer - Software on computer enables music
to be stored, displayed on monitor as a
musical score, edited by adding, deleting
and moving notes
- Music from different instruments can be added
as new tracks - so 1 musician can create effect of whole orchestra By Holly Evans Year 10
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