Many plastic cards, such as credit cards, have a strip of material that can be magnetised on the back. Data can be stored here in the form of magnetised dots.
Usually the data stored on this strip in the same data shown on the front of the card (e.g. the credit card number, expiry date and customer name).
The stripe allows this data to be input to a computer system faster and more accurately than by typing it in.
A magnetic strip/stripe reader is used to read the data from the stripe. This is usually done by ‘swiping’ the card through a slot on the reader.
Smart Card / 'Chip' Reader
Modern credit cards and ID cards don’t use a magnetic strip. Instead they have a tiny ‘chip’ of computer memory embedded inside them. (These cards are often referred to as smart cards.)
Data can be stored in this memory and read back using a ‘chip’ reader.
A card is inserted into the reader where metal contacts connect to the metal pads on the front face of the card. The reader can then access the memory chip and the data stored on it.
Smart cards can store much more data than magnetic strip cards, e.g. an ID smart card would store not only the owner’s name and card number, but might also have a digital image of the person.
Satellite TV decoders use smart cards to store which channels a user has paid for. The data is encrypted so that it is not easy to alter (you can’t add new channels without paying!)
Many types of card use this system: id cards, phone cards, credit cards, door security cards, etc.
Reading Text/ Codes
All data could be input to a computer using a keyboard, but this would often be a slow process, and mistakes would be made.
Sometimes speed and accuracy is required...
MICR Reader
Magnetic Ink Character Recognition (MICR) is a technology that allows details from bank cheques to be read into a computer quickly and accurately.
The cheque number and bank account number are printed at the bottom of each bank cheque in special magnetic ink using a special font. These numbers can be detected by an MICR reader.
OMR Scanner
Optical Mark Recognition (OMR) is a technology that allows the data from a multiple-choice type form to be read quickly and accurately into a computer.
Special OMR forms are used which have spaces that can be coloured in (usually using a pencil). These marks can then be detected by an OMR scanner.
Common uses of OMR are multiple-choice exam answer sheets and lottery number forms.
OCR Scanner
Optical Character Recognition (OCR) is a software technology that can convert images of text into an actual text file that can then be edited, e.g. using word-processing software). The result is just as if the text had been typed in by hand.
OCR is typically used after a page of a book has been scanned. The scanned image of the page is then analysed by the OCR software which looks for recognisable letter shapes and generates a matching text file.
Advanced OCR software can recognise normal handwriting as well as printed text - this is usually called handwriting recognition.
Barcode Reader / Scanner
A barcode is simply a numeric code represented as a series of lines.
These lines can be read by a barcode reader/scanner.
The most common use of barcode readers is at Point-of-Sale (POS) in a shop. The code for each item to be purchased needs to be entered into the computer. Reading the barcode is far quicker and more accurate than typing in each code using a keypad.
Barcode can be found on many other items that have numeric codes which have to be read quickly and accurately - for example ID cards.
SENSORS
A normal PC has no way of knowing what is happening in the real world around it. It doesn’t know if it is light or dark, hot or cold, quiet or noisy. How do we know what is happening around us? We use our eyes, our ears, our mouth, our nose and our skin - our senses.
A normal PC has no senses, but we can give it some: We can connect sensors to it...
A sensor is a device that converts a real-world property (e.g. temperature) into data that a computer can process.
Examples of sensors and the properties they detect are... Sensor What it Detects
Temperature Temperature
Light Light / dark
Pressure Pressure (e.g. someone standing on it)
Moisture Dampness / dryness
Water-level How full / empty a container is
Movement Movement nearby
Proximity How close / far something is
Switch or button If something is touching / pressing it
A sensor measures a specific property data and sends a signal to the computer. Usually this is an analogue signal so it needs to be converted into digital data for the computer to process. This is done using by an Analogue-to-Digital Converter (ADC).
Sensors are used extensively in monitoring / measuring / data logging systems, and also in computer control systems.
No comments:
Post a Comment