Proximity Sensor Threshold Setting for Constant Oscillation Current
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Solution Overview
Problem
Conventional proximity sensors face challenges in changing detection distance without increasing consumption current, as altering detection distance leads to changes in feedback current and oscillation circuit consumption.
Innovation Solution
The proximity sensor employs an oscillation circuit with a feedback current that adjusts oscillation amplitude, using a comparing part to set thresholds based on voltage and current signals, allowing for precise control of detection distance without significant changes in consumption current, utilizing D/A conversion circuits with optimized bit numbers for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the feedback current is changed to set the oscillation amplitude at a predetermined value to change detection distance, then the detection distance can be adjusted, but the consumption current of the oscillation circuit increases
Solution Approach 1:
The patent changes the threshold parameter of the comparison circuit instead of changing the feedback current. By adjusting the threshold voltage value that corresponds to different detection distances, the system achieves detection distance adjustment without changing the oscillation circuit's consumption current, as the feedback current remains constant while only the comparison threshold varies.
2Reliability
If the feedback current is increased to maintain oscillation amplitude at a predetermined value when detection distance is shortened, then the oscillation amplitude can be maintained, but the consumption current increases
Solution Approach 1:
The patent uses feedback from the oscillation circuit to dynamically adjust the threshold value in the comparison circuit. The feedback mechanism monitors the oscillation amplitude and adjusts the threshold accordingly to maintain stable detection without requiring changes in feedback current, thus maintaining constant consumption current while ensuring oscillation amplitude stability.
3Adaptability or versatility
If conventional methods are used to change detection distance by adjusting feedback current, then detection distance can be changed, but the consumption current differs with detection distance
Solution Approach 1:
The patent separates the detection distance adjustment function from the feedback current control. Instead of using a single feedback current adjustment mechanism, it divides the system into two independent parts: the oscillation circuit that maintains constant current operation, and the comparison circuit that adjusts threshold values to achieve different detection distances, thereby maintaining consistent consumption current across different detection distances.
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
This configuration allows for flexible detection distance adjustment while minimizing changes in consumption current, reducing circuit area and part costs, and enabling precise detection of target objects.
Implementation Method 1
an oscillation circuit including a coil and having an oscillation amplitude that changes with a feedback current
Implementation Method 2
a comparing part comparing the oscillation amplitude with a threshold
Data Source
AI summary
A proximity sensor and a method of changing a detection distance are provided to suppress changes in a consumption current of an oscillation circuit. The proximity sensor includes an oscillation circuit having an oscillation amplitude that changes with a feedback current, a comparing part comparing the oscillation amplitude with a threshold, a detecting part detecting a target object based on a comparison result of the comparing part, a voltage value signal generating part generating a voltage value signal based on the feedback current and the detection distance, a threshold setting part setting an analog signal converted from the voltage value signal as the threshold, a current value signal generating part generating a current value signal based on the detection distance and the voltage value signal, and a current value setting part setting an analog signal converted from the current value signal as a current value of the feedback current.