Barcode Reader

Barcode Reader

1. Barcode readers are a form of hardware used in shops to allow cashiers to easily find and sum up the prices of products.

2. Firstly, a light is shone onto the barcode to be read. Full coverage of the barcode is achieved using a mirror or prism.

3. Light reflects back off of the barcode in a pattern unique to the barcode due to the white sections reflecting more light than the black.

4. The light reflects onto a CCD (charged-coupled device) which measures the intensity of the light reflecting onto it in different areas and outputs corresponding electrical signals for each section of the CCD.

5. The electrical signals are transferred to the computer where software converts them into binary data.

6. The binary data for the barcode is checked against known barcodes in a database, which then returns the appropriate price for the scanned item.

7. Check Digit

   • The check digit is the final digit in the barcode's ISBN number and is used to check that the scanned barcode is valid.
   • The twelve non-check digits read by the barcode scanner are used as inputs for an algorithm. If the end result of this algorithm is the same as the check digit then the code is accepted. Otherwise it is rejected.