Digital barcodes work by encoding data in a visual pattern that a scanner can interpret and translate into readable text or numbers. The scanner's sensor detects reflected light from the barcode, converting it into an electrical signal which is then decoded.
Here's a breakdown of the process:
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Illumination: The barcode scanner shines a red light (or another suitable light) onto the barcode. This light source illuminates the barcode's pattern of dark and light bars.
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Light Reflection: The white spaces in the barcode reflect the light, while the dark bars absorb it. This creates a pattern of reflected light that corresponds to the barcode's specific arrangement.
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Sensing: A sensor within the barcode scanner detects the reflected light. This sensor is typically a photodiode or a CCD (charge-coupled device).
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Analog Signal Generation: The sensor converts the varying intensities of reflected light into an analog electrical signal. The strength of the signal corresponds to the amount of light reflected at each point.
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Decoding: The analog signal is sent to a decoder within the scanner or connected device. The decoder analyzes the signal and identifies the patterns of bars and spaces.
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Validation (Check Digit): Many barcode systems include a check digit. The decoder uses an algorithm to verify the integrity of the scanned data against the check digit. This helps ensure that the barcode was read correctly and prevents errors.
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Conversion to Text: The decoder translates the barcode pattern into its corresponding text or numerical representation. This is done based on the specific barcode symbology (e.g., Code 39, Code 128, EAN, UPC) used to encode the data. Each symbology has its own rules for representing characters using bars and spaces.
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Data Transmission: The decoded text or numerical data is then transmitted to a computer system or other device for processing.
Here's a table summarizing the key steps:
| Step | Description |
|---|---|
| Illumination | Scanner emits light onto the barcode. |
| Light Reflection | White spaces reflect light; dark bars absorb it. |
| Sensing | Sensor detects reflected light and its varying intensities. |
| Analog Signal | Sensor converts light intensity into an analog electrical signal. |
| Decoding | Decoder analyzes the analog signal to identify bar/space patterns. |
| Validation | Decoder verifies data integrity using a check digit (if present). |
| Text Conversion | Decoder translates the bar/space pattern into corresponding text/numerical data. |
| Data Transmission | Decoded data is sent to a computer or other device. |
In essence, a barcode scanner uses light to "read" the unique arrangement of bars and spaces in a barcode, then translates that pattern into meaningful information. The check digit then makes sure the data read is correct.
