Proximity Sensor Threshold Control for Low-Current Distance Switching
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Solution Overview
Problem
Conventional proximity sensors face challenges in changing detection distance without increasing the consumption current of the oscillation circuit, especially when shortening the detection distance, as this results in higher feedback current and increased power consumption.
Innovation Solution
A proximity sensor system that adjusts the feedback current by generating a voltage value signal based on the relationship between oscillation amplitude, feedback current, and detection distance, allowing for precise control of the oscillation amplitude and reduced consumption current, using a memory to store and update the feedback current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the detection distance is shortened, then the conductance of the resonance circuit increases, but the feedback current increases and the consumption current of the oscillation circuit increases
Solution Approach 1:
The patent changes the threshold value parameter dynamically based on detection distance. When detection distance is shortened, the threshold value is adjusted accordingly, allowing the system to maintain proper operation while accepting that feedback current and consumption current will increase. This parameter adaptation resolves the contradiction by making the system's response characteristics match the changed detection conditions.
2Stability of the object's composition
If the feedback current is increased to maintain oscillation amplitude at a predetermined value when detection distance is shortened, then the oscillation amplitude remains stable, but the consumption current of the oscillation circuit increases
Solution Approach 1:
The patent implements dynamic adjustment of the threshold value based on detection distance. Rather than maintaining a fixed threshold, the system adapts the threshold parameter to match current detection conditions, allowing optimal performance across varying detection distances while being aware of the associated current consumption changes.
Solution Approach 2:
The threshold value is changed as a parameter adaptation when detection distance changes. This allows the oscillation circuit to maintain stable operation at each detection distance setting, with the understanding that consumption current will vary accordingly based on the detection distance and required feedback current.
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 approach effectively suppresses the change in consumption current due to detection distance changes, enabling efficient detection while minimizing power consumption and allowing for flexible detection distance adjustments.
Implementation Method 1
an oscillation circuit 10 including a resonance circuit 11 and a feedback current changing circuit 12
Implementation Method 2
a resonance circuit constituted by the two-thread coil and the capacitor is driven externally at a constant frequency
Data Source
Figure 1
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AI summary
A proximity sensor (100) and a method of changing a detection distance are provided to suppress changes in a consumption current of an oscillation circuit (10) due to a detection distance. The proximity sensor (100) includes an oscillation circuit (10) including a coil (11a) and having an oscillation amplitude that changes with a feedback current, a comparing part (20) comparing the oscillation amplitude with a threshold, and a detecting part (31) detecting a target object (TA) based on a comparison result of the comparing part (20), a voltage value signal generating part (32) generating a voltage value signal indicating a digital quantity of a voltage value based on the feedback current and the detection distance indicating a distance from the coil (11a) to a position where the target object (TA) can be detected, a threshold setting part (40) setting an analog signal converted from the voltage value signal as the threshold, a current value signal generating part (33) generating a current value signal indicating a digital quantity of a current value based on the detection distance and the voltage value signal, and a current value setting part (50) setting an analog signal converted from the current value signal as a current value of the feedback current.