Flashcards in External Hardware Devices Deck (23)
What is a barcode?
- A set of vertical lines of different thickness that represent a number
What do the lines on Barcodes represent?
-Information about the manufacturer
-The product code
What are the 4 types of Barcode readers and what do they do?
-CCD (charged couple device) readers
-They are used to input data from barcodes
Where are pictures taken on a digital camera stored?
On a memory card
How are pictures transferred to a computer?
-By plugging the memory card into a computer card reader.
How do digital cameras work
1) When a picture is taken the image strikes the camera sensor
2) The sensor records the amount of light received and converts it into a digital value/binary
3) The image sensor records in RGB format so that all the colours can be created within the image
4) The picture is then stored as an image file on the memory card
5) The image file contains a data for each pixel in the image
What can image editing software be used to modify in a picture taken by a digital camera that has been and imported onto a computer?
- Red eye removal
- Cropping the image
- Modifying the brightness
What is the main advantage of laser printers over other types of printers?
They have a fast print speed.
They have a high quality dry page output.
What does RFID stand for?
Radio Frequency Identification tags
What are RFID tags used for?
- Can identify and track products
- Can be used for security purposes in stores to prevent theft as it can set off an alarm
How does the RFID reader operate?
- The RFID reader transmits a radio signal
-The RFID tags antenna receives it and returns a programmed information code to the reader.
- The code is translated into digital data which is interpreted by the computer to identify the information received.
Advantages of using RFID over barcodes
The tags don't require a power source as the signal from the reader energises the passive tag and causes it to transmit its ID code
How do laser printers work?
- The print drum is coated in positive static charge
- The printer generates the bitmap image of the page
- Laser beams are directed at print drum via a rotating mirror
- The laser reverses electric charge on drum to produce dark areas
- Toner is given positive charge
- Charged drum picks up toner from drum mechanisms
- The toner is transferred from drum to paper
- The toner is fused into the paper using heat and pressure.
What are the two types of barcodes
How do pen readers read a barcode?
- The tip of the pen is dragged across the barcode
-The photodiode measures the intensity of the light reflected back
- It creates a voltage waveform which is used to measure the widths of the bars/spaces
- This can be translated into 1's and 0's, which can be identified as product codes
What is an advantage of using pen readers over other types of barcode readers?
-They are the most durable due to their simple design
What is a disadvantage of using pen readers over other types of barcode readers?
-They have a limited use as they must come in contact with the barcode to work
How do laser scanner read a barcode?
- A laser beam reflects off a mirror allowing the barcode to be read in different positions
-The photodiode measures the intensity of the light reflected back from the laser beam
- It creates a voltage waveform which represents the widths of the bars/spaces
- This can be translated into 1's and 0's, which can identify product codes
What is an advantage of using laser scanners over other types of barcode readers?
-They are reliable
-The barcode can be read from different positions
- They don't have to come into direct contact with the barcode to work
How do charged couple devices read a barcode?
-They use an array of hundreds of tiny light sensors lined up in a row
- Each sensor measures the intensity of the light immediately in front of it
-This generates an identical voltage pattern to the barcode by sequentially measures the voltages across each sensor
How do camera based readers read a barcode?
-uses a camera and image processing techniques to decode a 1d or 2d barcode
What is an advantage of using camera based readers over other types of barcode readers?
-they can read barcodes that have been damaged or poorly printed
-can read barcodes that are a variety of distances away from the scanner