Light Receiving Apparatus Noise Measurement via Variable Threshold
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Solution Overview
Problem
Existing light receiving apparatuses face challenges in measuring noise levels without upsizing, which can lead to erroneous detection of noise as signals and failure to detect distant or low-reflectance objects, while incorporating dedicated noise detection apparatuses would increase the system's size.
Innovation Solution
A noise measurement system that uses a light receiving element and a binarization circuit to estimate noise levels by comparing voltage values with a variable threshold, calculating noise levels based on the number of times signals exceed the threshold, and setting an appropriate threshold voltage for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated noise detection apparatus is incorporated to measure noise levels, then measurement precision is improved, but device complexity increases and apparatus size increases
Solution Approach 1:
The patent merges the noise detection function with the existing light receiving apparatus by using the same light receiving element for both signal detection and noise measurement. The control unit integrates noise level measurement with the primary detection operations, eliminating the need for separate dedicated noise detection hardware and reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The light receiving element is designed to serve multiple functions: detecting target objects during normal operation and measuring noise levels when no target is present. The control unit automatically switches between these functions based on detection conditions, allowing a single component to perform both signal detection and noise measurement without requiring additional specialized apparatus.
2Measurement precision
If the apparatus is upsized to incorporate noise measurement capabilities, then measurement precision is improved, but the apparatus volume increases
Solution Approach 1:
The patent combines noise measurement functionality within the existing apparatus volume by utilizing the same light receiving element and control unit. No additional physical space is required as the noise measurement is performed through software control and signal processing within the existing hardware architecture, maintaining compact apparatus size.
Solution Approach 2:
The light receiving apparatus performs its own noise measurement using its existing components without requiring external dedicated noise measurement equipment. The control unit automatically measures noise levels by analyzing signals from the light receiving element during periods when no target object is detected, allowing the apparatus to self-diagnose and adapt to environmental noise conditions.
3Device complexity
If a fixed threshold is used for signal detection, then device complexity is reduced, but measurement precision deteriorates due to inability to adapt to varying noise levels
Solution Approach 1:
The patent implements dynamic threshold adjustment where the control unit automatically modifies the detection threshold based on measured noise levels. When environmental noise increases, the threshold is raised accordingly to prevent false detections, while maintaining lower thresholds in quiet conditions for maximum sensitivity. This dynamic adaptation significantly improves detection accuracy without requiring complex manual threshold management.
Solution Approach 2:
The control unit continuously monitors the output signals from the light receiving element, measures noise levels, and uses this feedback information to automatically adjust the detection threshold. This closed-loop feedback mechanism ensures the threshold remains optimally adapted to current environmental conditions, improving measurement precision while keeping the control system relatively simple through automated rather than manual adjustment.
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 accurate measurement of noise levels without upsizing the apparatus, reducing the probability of noise detection errors and enhancing the ability to detect distant and low-reflectance objects while maintaining system compactness.
Implementation Method 1
a light receiving element receiving light and photoelectrically converting the light into electrical signals
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
A light receiving apparatus includes a light receiving unit (40) including a light receiving element (41) that receives light and photoelectrically converts the light into signals; a threshold varying unit configured to vary a threshold; a comparing unit (56) configured to compare signal values of the signals output from the light receiving unit (40) with a variable threshold changed by the threshold varying unit, and output signals indicating a comparison result; a counting unit configured to count, for each of the thresholds, a number of times that signals indicating that the signal value is larger than the variable threshold is output from the comparing unit (56); and a calculating unit configured to calculate a level of a noise included in the output signals based on a count result in the counting unit.