Barcode Reader Signal Processing with Dynamic Gain and Offset Adjustment
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Solution Overview
Problem
Conventional bar-code readers face decoding errors due to defects such as insufficient contrast ratio in bar-codes and improper alignment of the sensor, leading to issues with amplitude and offset of the power voltage wave shape, resulting in incomplete or incorrect data capture.
Innovation Solution
A signal processing device with a variable amplifier, comparing means, detecting means, and adjusting means that adjusts the offset and gain of the amplifier based on comparisons with multiple thresholds to ensure the output signal falls within a valid operating range, thereby correcting amplitude and offset deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bar-code reader uses a fixed amplifier with constant offset and gain, then the device structure is simple, but it cannot accurately read defective bar-codes or bar-codes with improper alignment
Solution Approach 1:
The patent applies dynamics by making the amplifier parameters (offset and gain) variable rather than fixed. The offset adjustment element and gain adjustment element allow dynamic modification of the amplifier characteristics based on the actual signal conditions, enabling accurate reading of defective bar-codes while maintaining manageable system complexity through automated control
Solution Approach 2:
The patent implements feedback through the detection unit that monitors the output signal characteristics and feeds this information back to the control unit. The control unit then adjusts the offset and gain elements accordingly, creating a closed-loop system that automatically adapts to varying bar-code conditions and maintains high reading accuracy
2Measurement precision
If the amplifier output signal amplitude is too small, then the device can handle weak signals, but the signal may fall outside the operating voltage range causing data loss
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gain parameter of the amplifier. When the output signal amplitude is detected to be too small, the gain adjustment element increases the amplification factor, scaling the signal up to within the acceptable operating voltage range while maintaining the relative amplitude relationships needed for accurate bar-code decoding
3Adaptability or versatility
If the amplifier output signal offset is shifted, then the signal can adapt to different baseline levels, but the signal center may depart from the operating voltage center causing reading errors
Solution Approach 1:
The patent applies dynamics by implementing dynamic offset adjustment through the offset adjustment element. The detection unit continuously monitors the signal offset and the control unit dynamically modifies the offset element to center the signal within the operating voltage range, allowing the system to adapt to different baseline levels while maintaining precise signal centering
Solution Approach 2:
The patent implements feedback by having the detection unit measure the actual offset of the amplifier output signal and feed this information back to the control unit. The control unit then adjusts the offset element accordingly, creating a closed-loop system that automatically centers the signal waveform within the operating voltage range regardless of initial offset conditions
Data Source
AI summary
There is provided a signal processing device for remedying an error in reading bar-codes derived from a defect of the bar-code printed on a label, a way to hold the bar-code reader's sensor to the bar-code and so forth. The signal processing device comprises: a variable amplifier configured to output a signal, as an output signal thereof, corresponding to an input signal, an offset and a gain of the variable amplifier being able to be adjusted; a comparing means configured to compare a level of the output signal of the variable amplifier with a plurality of thresholds; a detecting means configured to detect either or both of a shift of the offset of the variable amplifier and an excess or deficiency of the gain of the variable amplifier based on the result of the comparison executed in the comparing means; and an adjusting means configured to adjust either or both of the offset and the gain of the variable amplifier based on the result of the detection executed in the detecting means.