Optical Proximity Detector Open Loop Correction
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Solution Overview
Problem
Optical proximity detectors face challenges in accurately detecting distance and motion due to dynamic variations in gain and phase offsets, crosstalk, and residual errors, which affect the precision and reliability of distance measurements.
Innovation Solution
The optical proximity detector employs a digital back-end circuitry that includes dynamic gain and phase offset correction, crosstalk correction, and static phase offset correction, along with precision estimation, using IQ demodulation and calibration techniques to enhance accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dynamic gain and phase offset correction is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent performs gain and phase offset corrections in advance through calibration procedures before actual distance measurements are taken. The system pre-determines correction values and applies them during operation, which improves measurement precision without requiring complex real-time computation during the actual measurement process.
Solution Approach 2:
The patent introduces intermediate correction signals and calibration data as mediators between the raw detector output and the final distance measurement. These intermediate elements facilitate the correction of dynamic variations without requiring direct complex processing of the primary measurement signal.
2Reliability
If crosstalk correction is applied, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and separates the crosstalk component from the total detected signal through dedicated calibration measurements. By isolating the crosstalk effect during calibration and removing it through subtraction or compensation, the system improves detection reliability without requiring complex real-time filtering during normal operation.
3Measurement precision
If multiple correction techniques are used, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs multiple correction calibrations in advance during manufacturing or initial setup, storing the correction parameters for later use. This preliminary action allows the system to apply pre-computed corrections during operation without incurring time penalties during actual distance measurements.
Solution Approach 2:
The patent implements a hierarchical correction approach where essential corrections are applied continuously while less critical corrections are applied periodically or selectively. This partial action approach maintains measurement precision while reducing the overall time burden of multiple correction techniques.
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 improves the accuracy and reliability of distance measurements by compensating for dynamic variations and residual errors, providing precise distance and motion detection, and enabling precise control of subsystems in applications like mobile devices.
Implementation Method 1
detect the presence of an object, estimate proximity of (e.g., distance to) an object and/or detect motion of an object, based on the light originating from the light source that is reflected from an object and detected by the light detector
Implementation Method 2
Where such detectors rely on time-of-flight (TOF) principles to detect distance to an object
Implementation Method 3
an adjacent photosensitive light detector
Data Source
AI summary
An optical proximity detector includes a driver, light detector, analog front-end, sensor(s) that sense correction factor(s) (e.g., temperature, supply voltage and/or forward voltage drop), and a digital back end. The driver drives the light source to emit light. The light detector produces a light detection signal indicative of a magnitude and a phase of a portion of the emitted light that reflects off an object and is incident on the light detector. The analog front-end receives the light detection signal and outputs a digital light detection signal, or digital in-phase and quadrature-phase signals, which are provided to the digital back-end. The digital back-end performs closed loop correction(s) for dynamic variation(s) in gain and/or phase caused by a portion of the analog front-end, uses polynomial equation(s) and sensed correction factor(s) to perform open loop correction(s) for dynamic variations in temperature, supply voltage and/or forward voltage drop, and outputs a distance value.