What types of Bar Code readers are available?

Currently, the four different types of bar code readers available are the pen type readers (bar code wands), laser bar code scanners, CCD (Charge Couple Devices) barcode readers and camera based barcode readers. Each of these types use a slightly different Technology for reading and decoding a bar code.

Pen Type Readers or Bar Code wands

Pen type barcode readers have a light source and a photo diode placed next to each other in the tip of a pen or wand. To read a bar code, you drag the tip of the pen across all the bars, in a steady even motion. The photo diode measures the intensity of the light reflected back from the light source and generates a waveform corresponding to the widths of the bars and spaces in the bar code. The barcode reader sends the waveform to the decoder, which decodes the waveform and sends it to the computer in a traditional data format.

Laser Barcode Scanners

Laser barcode scanners work the same way as pen type barcode readers. The only main difference is that Laser barcode scanners use a laser beam as their light source, and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. As with the pen type bar code reader, a photo diode is used to measure the intensity of the light reflected back from the bar code.

CCD Barcode Scanners

CCD barcode scanners use an array of tiny light sensors lined up in a row in the head of the barcode reader. Voltage waveform corresponding to the bars and spaces of the bar code is generated and sent to the decoder, which decodes the data and sends it to the computer. The main difference between a CCD barcode scanner, a pen type barcode scanner, and laser barcode scanner is that the CCD barcode scanner measures emitted ambient light from the bar code whereas pen or laser barcode scanners measure reflected light of a specific frequency originating from the scann
er itself.

Camera Based Barcode Readers

The camera based barcode readers use a small video camera to capture an image of a bar code. The barcode reader then uses sophisticated digital image processing techniques to decode the bar code.

How can I connect my Bar Code Scanner to my computer?

Bar code readers come in either "keyboard wedge" output or RS232 output. A bar code reader with keyboard wedge output plugs directly into the keyboard port on your computer and also provides a pigtail connector to plug in your keyboard simultaneously. When a bar code is scanned with the keyboard wedge bar code reader, the bar code data goes into the computer as if it were typed in on the keyboard.

Advantages of the keyboard wedge

Simple and easy to interface to the computer. No software is required.

Disadvantages of the keyboard wedge

1. When you scan a bar code, the cursor has to be in the correct input data field, and in the correct application otherwise the bar code data will end up in whatever application that is active. This can cause all sorts of problems.
2. The keyboard output is limited, in the sense that you cannot modify the data in any way before sending it into the program in the computer. For example, if you needed to parse a bar code message into multiple pieces or remove some of a bar code messages, you can not.

Advantages of Bar code reader with RS232 or "Serial Interface"

1. This type of bar code reader is connected to an available serial port on the back of your computer.
2. When you read a bar code, you have control over how and where your data goes.
3. You can perform any modifications on the bar code data before sending it to the computer or translating the data.

Disadvantages of Bar code reader with RS232 or "Serial Interface"