Photoelectric Sensor Signal Chains for Wide Dynamic Range
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Solution Overview
Problem
Existing photoelectric sensors require expensive transimpedance amplifiers for each low and high sensitivity receive path, increasing component costs.
Innovation Solution
A photoelectric sensor with dual signal processing chains, each with different amplification factors and thresholds, allows for wide dynamic range detection without multiple transimpedance amplifiers, using a first and second amplifier with specific threshold and amplification ratio relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transimpedance amplifiers are used for low and high sensitivity receive paths, then the dynamic range detection capability is improved, but the component cost increases
Solution Approach 1:
The patent merges the functions of multiple transimpedance amplifiers into a single transimpedance amplifier by using a current summing node that combines currents from multiple photodetectors. This consolidation maintains the wide dynamic range detection capability while reducing component count and cost.
Solution Approach 2:
The single transimpedance amplifier is designed to handle multiple input currents from different photodetectors simultaneously, making it a multi-functional component that replaces what would traditionally require multiple separate amplifiers. The amplifier processes signals across the full dynamic range by receiving combined currents from both low-sensitivity and high-sensitivity photodetector paths.
2Ease of manufacture
If a single transimpedance amplifier is used, then the component cost is reduced, but the dynamic range detection capability may be compromised
Solution Approach 1:
The patent segments the detection function into multiple photodetectors with different sensitivity characteristics (low-sensitivity and high-sensitivity photodetectors) that feed into a common transimpedance amplifier. This segmentation allows the system to handle different signal intensity ranges while using a single amplifier, maintaining detection capability across a wide dynamic range.
Solution Approach 2:
The current summing node acts as an intermediary that combines currents from multiple photodetectors before they reach the transimpedance amplifier. This intermediary structure enables the single amplifier to process signals from multiple detection paths with different sensitivities, preserving the wide dynamic range capability while reducing component count.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables cost-effective detection of light over a wide dynamic range with accurate distance calculation, using a single preamplifier and dual amplifiers with distinct thresholds and gains to enhance sensitivity and precision.
Implementation Method 1
a light receiving unit (3) configured to convert reflected light into a current signal
Data Source
AI summary
A photoelectric sensor includes: a first signal processing chain including a first amplifier configured to amplify an output signal from a preamplifier by a first amplification factor A1 and a first binarization circuit configured to binarize an output signal from the first amplifier by a first threshold Vth1; and a second signal processing chain including a second amplifier configured to amplify an output signal from the preamplifier by a second amplification factor A2 and a second binarization circuit configured to binarize an output signal from the second amplifier by a second threshold Vth2. The first threshold and the second threshold, and the first amplification factor and the second amplification factor satisfy the following relational expression: 1<(Vth2/Vth1)<α=(A2/A1).