topic 5 - input & output device Flashcards
Input Device =
A device that allows data to be entered into a system
Output Device=
A device that allows the user to see/hear data
how does a 2D Scanner work (5)
- Paper placed on a glass panel
- Bright light illuminates the document (modern scanners use a xenon light)
- Scan head moves across the document
- Lens focuses on the document image
- Scanned image turned into electric form by the CCD
application of 2D scanner (2)
- At airports to read passports
- OCR software used to read text
application of 3D scanner (2)
- CT Scanners
- MRI Scanners
how does a barcode Scanner work (6)
- Red laser shone at barcode
- Light is reflected back
- Sensors detect the light back
- Pattern converted to digital
- Microprocessor interprets the data
- Each digit made up of 2 dark and 2 white lines
advantage of using a barcode scanner to the company (3)
- Easy to change prices on stock items
- No need to price every item on the shelf
- Allow for automatic stock control
advantage of using a barcode scanner to the customers (3)
- Faster checkout
- Reduces errors
- Itemized bills
how does a QR code Scanner work (8)
- QR Code scanned by camera
- Light reflected back
- Black squares reflect less than white squares
- Three large squares used to define alignment
- Squares data is decoded – each square has a binary value
- Processed by an app
- Links to website or document
- QR code can be saved and used again
QR Code v Barcode (4)
- Barcode 1D QR is 2D
- QR code can contain more data
- QR code can be read from any angle
- QR codes faster to scan than bar codes
Benefits Concept Keyboard (3)
- Fewer typing errors because one button is pressed to order an item
- Speeds up time to order because fewer buttons pressed
- May require less training
how does a microphone work (2)
- A diaphragm vibrates producing an electric signal
- Signal goes to a sound card and is converted into digital values
how does Voice recognition system work (4)
- Users voice converted into digital signal
- Spoken words produce a digital pattern
- Software compares wave pattern to patterns stored in memory
- If they match person is identified
speech recognition=
Spoken words recognized and shown on screen
problems of speech recognition (2)
- The software needs to be trained
- Some dialects and accents can cause problems
application of speech recognition (2)
- Cars
- Siri
how does resistive touch screen work? (2)
- Uses multiple layers of material that transmit electric current
- When top layer is touched into the lower layer current changes and location is found
advantage of resistive touch screen (2)
- Cheap to make
- Can use when wearing a glove
how does Capacitive touch screen work (4)
- Conductive layer
- Current flows from 4 corners – electric field created
- Sensors monitor field
- When screen is touched charge transferred to finger - current changes and location is calculated
disadvantage of resistive touch screen (3)
- Poor in sunlight
- Easily scratched
- Doesn’t allow multi touch
advantage of capacitive touch screen (3)
- Good in sunlight
- Durable
- Allows multi touch
disadvantage of capacitive touch screen (2)
- Screen can crack on impact
- Can’t use while wearing gloves
how does infra red work? (2)
- Invisible grid of infra-red beams on screen
2. When screen is touched beam is broken and location is calculated
advantage of infra red (3)
- Durable
- Allows multi touch
- Can use with gloves
disadvantage of infra red (3)
- Expensive to make
- Screen can crack on impact
- Sensitive to dirt
types of sensors (6)
1. Temperature Aircon, central heating 2. Motion Detects if an infra-red beam has been broken and sends a signal to the microprocessor 3. Pressure Detects a change in pressure and receives current if a circuit is created sending a signal to the microprocessor 4. pH 5. Light 6. Magnetic fields 7.Anti-lock brakes on a car
examples of Monitoring Applications (3)
- Burglar Alarm
- Street Lights
- ABS Brakes
Control Systems Process (7)
- Sensor detects input (Name the sensor)
- Analogue data converted to digital
- Signal sent to microprocessor
- Microprocessor compares signal to stored value
- If value outside range signal sent to device
- Actuator used to operate device
- Process is in a continuous loop
Printers (2)
- Interrupt - Signal sent to computer about no paper
- Buffer – Area of memory used to temporarily store data being sent to the printer
Types of Printer (3)
- Laser
- Inkjet
- 3D
Inkjet (8)
- Used for low quantities of documents
- Used for photographs
- Uses liquid ink cartridges
- Uses thermal bubble
- Rollers used to move the paper
- Uses a moving print head
- Sprays ink onto the paper
- Different colour inks are mixed to create required colours
Laser (5)
- Used for high volume quality output
- User toner cartridges
- Uses charged print drum
- Uses static electric charges
- Toner is fused to the paper
3D(4)
- Used to make physical model from blueprint
- Used to create physical model from CAD
- Uses resin
- Solid is built up in thin layers
- Uses inkjet technology with a moving head
Binder 3D printing (3)
- Similar to direct but uses two passes
- 1st pass sprays dry powder
- 2nd pass sprays a binder (type of glue)
2D & 3D Cutters(1)
-Very complex designs can be made as the cutters are controlled by computers
Speakers & Headphones(3)
- Sound produced by passing digital data through a digital to analogue converter (DAC) then through an amplifier
- Sound produced by voltage differences vibrating a cone
- Rate with which DAC can translate the digital signals is know as sampling rate
LCD & LED Screens Advantages over CRT(5)
- Brighter image
- Higher resolution
- Thinner screen
- Uses less power
- Last longer
OLED advantages(6)
- Organic layers are thinner, lighter and more flexible
- OLED layers can be made from plastic so are lighter
- Brighter than LED
- No backlighting required so use less power
- Can be made into large thin sheets for advertising boards
- Very large field of view
DLP projectors (4)
- Uses millions of micro mirrors on a DLP chip
- Micro mirrors can switch on/off thousands of times a second
- Bright white light passes through colour filter on its way to the DLP chip
- Light split into primary colours RGB
LCD projectors (6)
- Older technology than DLP
- Beam of light generated by a bulb
- Light sent to group of chromatic-coated mirrors that reflect the light back at different wavelengths corresponding to RGB
- Three different light components pass through three LCD screens
- Images are then combined using a prism to create full colour image
- Finally image passes through projector lens onto a screen
