In This mini series of blogs this week we’re looking at the types of Barcode technologies that are used and then looking at the Pro’s and cons of each one. Today it’s CCD barcode Scanners.
CCD Barcode Scanners basically have an array of tiny light sensors lined up in a row which are housed inside the in barcode scanner. There are hundreds of these sensors, each one measuring the level of the light intensity being reflected onto it from whatever is being scanned in from of it. These light sensors form the heart of the way barcodes are detected and deciphered in CCD barcode Readers and because each sensor is so small and that there are hundreds of them, a voltage pattern will be mimicked which is identical to the line pattern in the bar code being scanned. The CCD Barcode Scanner engine will then read these values sequentially, measuring the voltage values as it goes along and it is able to then create and read the barcode from this.
Basically where there is white, lots of light is bounced back and the value will be high, where it’s reading black the light tends to get absorbed by the barcode , thus bouncing very little back and the value will be near 0. You can start to understand now why barcode contrast can be an issue with colours like say black on yellow being an issue for some barcode scanners as the values can get too close and confuse the Barcode Reader.
The important difference between a CCD Barcode reader array and a laser scanner (Next blog) is the CCD barcode reader is measuring emitted “ambient” light from the bar code whereas laser barcode scanners measure only the reflected laser light originating from the scanner itself.
Pro’s of CCD Barcode Scanners
- Price – Cheaper technology to start with, smaller parts and a simpler technology and design mean CCD scanners are inherently cheaper.
- Ruggedness – No moving parts to break means that CCD barcode scanners tend to be inherently quite droppable!
- Safer – No Laser light to shine in people’s eyes. Yes believe it or not people still do this!
Cons of CCD barcode Readers
- Range – Due to the ambient light method it has poorer range than laser scanners. Whilst not necessarily true any more when talking about 30cm type of scanning distance, Laser still has the Extended range sewn up for now at least.
- Flexibility – Again newer CCD scanners are better but typically CCD tends to read a far tighter distance range, whereas laser tends to be more flexible.
Having said this CCD technology has come on leaps and bounds in the past few years and it is in many cases now equal, or even surpassing laser scanner technology. Motorola for instance are a long time advocate of Laser technology when it comes to barcode readers but they have announced recently that they will be replacing key models in it s “LS” series with CCD technology which leaves few cons for the technology.
Tomorrow we’ll continue with a look at Laser Scanner Technology
The Rugged and Mobile blog.