Input Devices Flashcards
What are barcodes used for today?
The identification of thousands of applications including tracking parcels, shipping cartons, passenger luggage, blood, tissue and organ products around the world
What are the two types of barcodes?
Linear (1D barcodes) and 2D barcodes (such as quick response, QR, code)
What barcodes can hold more information?
2D barcodes
What are the four types of barcode readers?
Pen-type scanners, laser scanners, CCD readers and camera-based readers
How does a pen-type reader, read a barcode?
The tip of the pen is dragged across all the bars at even speed, the photo diode measure the intensity of the light source and generates a waveform that is used to measure the width of the bars and spaces in the barcode
Describe a pen-type readers attributes?
In a pen-type reader, a light source and a photo diode are placed next to each other in the tip of the pen
What is an advantages of pen-type scanners?
Their simple design, pen-type scanners are the most durable type of barcode scanner, and can be tightly sealed against dust, dirt and other environmental hazards, their small size and low weight makes it suitable with portable computers or very low volume scanning applications
What is an disadvantage of pen-type scanners?
Their applications are limited because they must come into direct contact with a barcode to read it
How does laser scanners work?
It measure he intensity of light reflected back from the light source and generates a waveform that is used to measure the widths of the bars and spaces in the barcode, the same way as a pen scanner, but with laser beams as the light source
What is an advantage of laser scanners?
They are reliable and economical for low-volume applications
How does a camera-based reader work?
it uses a camera and image processing techniques to decode a 1D or 2D barcode by using an imaging scanner
What is an advantage of Camera-based scanners?
it can read a barcode on any surface, printed or onscreen, and can also read a code that is damaged or poorly printed
What are some of the uses of Camera-based scanners?
Scanning drivers licences, couponing, event ticketing, can be used by a cell phone
How does a digital camera work?
Uses CCD or CMOS (Complementary Metal Oxide Semiconductor) sensor comprising millions of tiny light sensors arranged in a grid, the binary data from each sensor is recorded onto the camera’s memory card so that the image can be reproduced using suitable software at a computer
What is an advantage of CCD?
It tends to produce higher quality images and are used in higher end cameras, they are more reliable since the technology has been around for much longer
What is an disadvantage of CCD?
They have higher power consumption, using up to 100 time that of a CMOS sensor
What is an example of a digital camera at work?
Mastercard app allows customers to make a purchase by taking a selfie rather than a password, there photograph of the user is converted into binary code using facial recognition technology, which is then compared with a stored code
What is the input device and output used by a Radio Frequency Identification (RFID)?
An input device to read the signal from an RFID chip, and output to transmit a signal from an active tag
What are RFID used for?
They are being used to identify and track things like household product and cards to bank cards and animals
What is an advantage of RFID?
They can read without a line of sight from up to 300 metres
Why are active tags larger than passive tags?
They include a battery to power the tag so that it actively transmits a signal for a reader to pick up
What is an advantage of a active tag?
They are used to track things likely to be read from further away
What is an advantage of a passive tag?
These are much cheaper to produce as they do not have a batter, relying on radio waves
How does a passive tag work?
The radio waves emitted from a reader up to a metre away provide sufficient electromagnetic power to the card using its coiled antenna, once energised, the transponder inside the RFID tag can send its data to the reader nearby
When are passive tags most common?
In tagging items, such as some grouches, music CDs and for smart cards such as Transport for London’s Oyster card or a contactless bank card
