Proximity Sensor Crosstalk Compensation With Coarse and Fine Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Proximity sensors face challenges in accurately detecting targets due to crosstalk noise from disturbing objects, which limits their range and resolution, especially in applications like mobile phones where crosstalk compensation is needed for extended ranges without compromising resolution.
Innovation Solution
The proximity sensor incorporates a crosstalk compensation circuit with two charging circuits, one for coarse compensation and another for fine compensation using an operational amplifier offset strategy, allowing it to estimate and cancel out crosstalk noise effectively, thereby extending the compensation range while maintaining high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If crosstalk compensation is implemented to extend detection range, then measurement range is improved, but device complexity increases due to additional charging circuits and control mechanisms
Solution Approach 1:
The crosstalk compensation is divided into two distinct stages: coarse compensation and fine compensation. The coarse compensation circuit handles the majority of crosstalk noise reduction, while the fine compensation circuit refines the result. This segmentation allows each circuit to be optimized for its specific function, managing overall complexity while achieving extended detection range with high precision.
Solution Approach 2:
The coarse compensation is performed first to remove the bulk of crosstalk noise before fine compensation is applied. This preliminary action reduces the burden on the fine compensation circuit, allowing it to focus on smaller residual errors and achieve higher precision without requiring excessive complexity.
2Device complexity
If single-stage crosstalk compensation is used, then device complexity is reduced, but measurement precision deteriorates due to limited compensation range
Solution Approach 1:
The compensation process is segmented into coarse and fine stages, each handling different levels of crosstalk noise. The coarse compensation circuit addresses large-scale crosstalk variations, while the fine compensation circuit handles subtle residual noise. This segmentation enables a wide overall compensation range while maintaining simplicity in each individual circuit stage.
Solution Approach 2:
The coarse compensation circuit applies a larger, more aggressive compensation action to handle the majority of crosstalk noise, while the fine compensation circuit applies a smaller, more precise action to refine the result. This partial action approach allows each circuit to operate within its optimal range, achieving wide overall compensation without excessive complexity.
3Device complexity
If coarse compensation only is applied, then device complexity is minimized, but measurement precision deteriorates due to residual crosstalk noise
Solution Approach 1:
The two-stage compensation structure separates coarse and fine compensation functions into distinct circuits. The coarse compensation handles dominant crosstalk components, while the fine compensation specifically targets residual noise that would otherwise degrade resolution. This segmentation achieves high precision without requiring a single overly complex circuit.
Solution Approach 2:
Coarse compensation is applied as a preliminary step to remove the bulk of crosstalk noise, preparing the signal for fine compensation. This preliminary action reduces the residual noise level, allowing the fine compensation circuit to achieve high resolution with minimal complexity by focusing only on the remaining small errors.
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 solution provides a wide crosstalk compensation range with fine resolution, enabling accurate target detection and distance measurement even in environments with strong crosstalk, such as no-hole mobile applications.
Implementation Method 1
an IR photodiode used in the receiving circuit as an optical detector. The reflected energy may be measured by evaluating the photo current
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A proximity sensor (1) with crosstalk compensation comprises a transmitting circuit (10) to transmit a signal to be reflected at a target (2) and a disturbing object (3), and a receiving circuit (20) to receive a reflected signal (RS) having a useful component (RS1) and a noise component (RS2). The receiving circuit (20) comprises an output node (A20) to provide an output signal (Vout2) in dependence from the distance of the proximity sensor (1) from the target (2). The receiving circuit (20) comprises a crosstalk compensation circuit (100) comprising a first charging circuit (110) to provide a first charge for for coarse crosstalk compensation and a second charging circuit (120) to provide a second charge for fine crosstalk compensation. A control circuit (30) sets an amount of the first and the second charge so that the output signal (Vout2) of the crosstalk compensation circuit (100) is dependent on the useful component (RS1) and independent on the noise component (RS2) of the reflected signal (RS).