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Transcript of Input Devices
Basic layout is smililar worldwide.
Some have a curved (ergonomic) key layout --> makes typing fater and more comfortable.
Entering data on a keyboard is quite slow. Mice Digital Cameras Used by people who are visually impaired (blind).
Consists of letter and symbols that are read by fingers moving across a series of dots.
To enter data is not impossible --> you can simply plug a Braille notetaker directly into a computer OR --> tactile overlays can be placed over certain keys on the QWERTY keyboard. Braille keyboards QWERTY keyboard Concept keyboard Consists of a flat panel of contact switches covered by a flexible membrane.
Each switch can be programmed to respond differently by the computer software.
Overlays, which have picture and symbols on them, are placed over the membrane.
Used in primary schools, restaurants, some supermarkets and hostile environments. How they work: --> some have a ball underneath the mouse which moves as the mouse is moved BUT --> most are optical (they use a light beam and detector instead).
Many use infra-red or wireless links to the computer so no connecting cable is necessary.
Most have a small wheel as well as the buttons. Standard Mouse Joysick Popular for computer games.
The hand grip can:
be moved around the central axis --> in any direction BUT it is spring-loaded to return to the centre when the hand pressure is released. Trackball similar to a mouse BUT the ball is on top of the it.
buttons work in the same way as a mouse. when the picture is taken, it is stored in a computer memory rather than on a film.
the pictures can be:
displayed on the computer monitor
imported into graphics/art program for editing
printed Web Cams Its a digital camera which, nowadays, is installed inside a computer BUT can also be separate from the computer and sit on or next to the computer.
can be used for video conferencing.
lower resolution and poorer quality than more expensive digital cameras. Video Capture They can be plugged straight into a computer --> this allows the computer to download, store and manipulate the digital video images.
Older camcorders need a video digistiser card fitted into a computer to connect to a computer. Touch Sensitive Input Devices Touch Pad Found on laptops.
Act in the same way as a mouse --> when you move your finger across the pad, the pointer on the screen moves. --> when you tap the pad lightly, it is like clicking the mouse button. Graphics Tablet flat pad.
user writes/draws on it using a stylus (similar to a pen)
as the stylus moves across the pad, the movement is changed to a drawing on the computer monitor. Touch Screen on touch sensitive screens there are criss-crossing beams of infra-red light in front of the glass on the monitor.
when a user touches the glass with their finger --> two sets of rays are blocked:
the rays traveling from side to side
the rays traveling from top to bottom.
the computer detects the finger's position from the light sensors placed on the opposite side of the monitor screen to the light sources..
user friendly Scanner Used to input picture and text into a computer.
How they work:
the picture is placed on a piece of glass
as a bright light moves across the picture the reflected light is focused onto a light-sensitive device
The scanned pictures can then be manipulated using a sophisticated image editing software. Scanners, OMR &OCR OMR (Optical Mark Reader) They detect marks made on paper.
How they work:
The reader scans across the paper using an infra-red light.
What happens when there is a mark: --> the reflection of light is reduced and this is inputted to the computer.
What happens when there isn't a mark: --> the reflection of the light on the white paper is strong. OCR (Optical Character Recognition) OCR software is used to recognise letters, numbers and words.
The ability to correctly scan the characters varies, depending on how clear the writings is.
it can read different styles and sizes of type and also neat handwriting. Light Input Devices Infra-Red Remote Control Used to change channels and volume of a TV or hi-fi.
How it Works:
when a button is pressed --> a series of light pulses are emitted by LED (Light-Emitting Code)
The infra-red receiver on the appliance picks up the beams of light.
The microprocessor the produces the output.
requires a line of sight.
can only travel a distance of 10 meters. Bar Code Reader They scan a bar code and translate it into data that can be processed by a computer.
How they work:
A laser absorbs the black bars/dots and the white bars/dots reflect the light
It then converts the data to text and passes it to a computer where it can be processed.
Can be hand-held or or fixed.
Can be pen-like devices ( Wand Bar Code Readers) Light Pen Used in art and design
Like a mouse
Connected to a computer by a a wire
How it works:
a light detector at the tip of the pen picks up light signals from the monitor. Banking Input Devices MICR (Magnetic Ink Character Recognition) Used on bank cheques (in important data at the bottom of the cheque)
How it works:
the ink on the cheque contains tiny magnetic particles --> these particles makes it possible for the data on the cheque to be read into the computer by machine.
fast and reliable method of reading data into a computer. Magnetic Stripe Stripes of magnetic tape found on the back of plastic cards e.g. credit card
How it Works:
When the card is swiped --> the stripe passes playback heads which reads data from the stripe. Smart Card AKA ICC (Intergrated Chip Card)
plastic card that has a tiny microprocessor chip.
How it works:
When a card is placed in a card machine --> the user has to enter a PIN (Personal Identification Number)
The PIN is entered using a numeric keypad
allows for more data to be stored on hte card
data is more secure numeric keypad Music and Microphones Microphone Programs recognise speech (input) and translate the words into a word processor.
When a word is said that can sound like another (e.g. weather and whether), the program can choose the correct word that fits the context.
People who are severely handicapped use these devices to communicate.
Useful for when the user's hands need to be free. MIDI (Musical Instrument Digital Interface) Made for linking musical keyboards and instruments together.
How it works:
When computers are fitted with MIDI interface boards --> they can be connected to MIDI instruments --> which allows music to be input and output from the computer.
Software on the computer lets:
music be stored.
music can be displayed on the monitor as a musical score.
music can be edited.
Input Devices used for Control Sensors input devices which are used when computers are used to monitor environments or control machines. They turn physical parameters such as pressure, light, humidity, temperature, liquid flow, linear movement, rotation or sound into digital signals that a computer can recognise.
e.g: Temperature Sensors can be used to:
monitor weather forecasting.
control washing machine water heating.
open greenhouse windows.
operate central heating.
Pressure Sensors can be used to:
sense body weight in a burglar alarm system.
air pressure in weather forecasting.
water depth and pressure in washing machines.
traffic passing along the road in a traffic monitoring system. Light Sensors can be used to:
sense daylight in greenhouses.
sense daylight in street lighting.
light beams and infra-red movement can help burglar detection.
video cameras can be used for capturing an image. Position Sensors can be used to:
sense the position of wind vanes.
sense the position of operating systems.
detect vibration (e.g. car alarms).
used in robotics.
used in GPS (global positioning systems).