4.7.4.1 Fo CompOrgArch (I/O Devices) Flashcards
(19 cards)
What are the 4 IO Devices
- Barcode Readers
- Digital Cameras
- Laser Printer
- RFID
What are common uses for barcode readers
- Delivery Items
- Tickets
- Items in shops
What are the two types of barcodes
- 1D (Linear)
- 2D (QR- Quick Response))
What is the main difference between 1D and 2D barcodes
- QR can hold more complex information than linear, and is usually used to redirect users to website URLs, whereas linear is used for goods sold in shops
What are the 4 type of barcode readers
PhotoDiode:
- Pen-Style
- Laser Scanners
Camera/CCD:
- Charge Coupled
- Camera based
What do pen style readers consist of
A light source and photodiode in the tip of the pen
How do photodiode readers work
- Light is shone
- The reader is dragged by user or moving mirror directs light across the barcode
- The black and white lines reflect different amounts of light
- The light sensor measures the intensity of reflected light
- Reflected light is converted to an electrical signal
- Signal is analysed to determine encoded barcode value
- This is transmitter to a computer and looked up in a database
How do Charge Couple and camera based Readers work
- Light is shone
- CCD/Camera measures light reflected from barcode
- Reflected light is converted to an electrical signal
- Image analysis software analyses image to determine value encoded in barcodem
How do digital cameras work
- Lens focuses light onto sensors
- Sensor is a photoelectric device which converts light into binary
- A shutter is pressed and opened for a moment allowing for light to enter through to sensors
- Sensor detects light and converts it to binary
- Image is recorded as an array of pixels
How do laser printers work
Printer generates a bitmap image
- The drum becomes negatively charged
- The guider laser beam is used to change the charge of the drum to attract the toner to the correct places
- The toner is given the opposite charge to the drum and is picked up by the drum
- After the toner sticks to the drum, it’s rolled onto the paper
- the paper is then passed through the fuser which binds the toner
How do laser printers produce colour
Different toner colours are put onto the page at different points of the printing, so for colour the page is passed multiple times
What does RFID stand for
Radio Frequency Identification
What does RFID allow for
The wireless transfer of data between a tag and a reader
What is RFID used for
- Contactless Payments
- Security passes
- Keyless Car ignition
What do RFID consist of
- A chip which contains a small amount of memory
- attached to a coil of wire that acts as an antenna
What are passive RFIDs
- RFIDs that induce power wirelessly from the reader to operate the chip
What are active RFIDs
- RFIDs that contain a small power supply meaning they can be used much further away from the reader
What happens when a passive RFID tag is scanned on the reader
- the reader emits radio waves which are picked up by the tag’s antenna
- The wave induces power in the tags antenna, enough so that the chip can emit a radio wave in response, which contains information held on the chip
- The reader picks this wave up and decodes the information and returns the information to the computer
3 comparisons between RFID and barcode usage
- RFID doesn’t require line of sight whereas barcodes do
- RFID can detect if an item has already been scanned
- active RFID can be used in further ranges
