Hybrid Proximity Sensor Circuitry for Hair- and Smudge-Robust Detection
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Solution Overview
Problem
Existing proximity sensors in electronic devices, such as cellular telephones, face challenges in accurately determining the proximity of a user's head due to variations in hair reflectivity and contamination, leading to false positives and negatives.
Innovation Solution
The integration of optical and electrical proximity sensor circuitry, including infrared light-emitting diodes and photodiodes for optical sensing, and coplanar or ring-shaped capacitive electrodes for electrical sensing, to generate an integrated sensor output signal that is processed to determine the presence of external objects, thereby improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical proximity sensor circuitry alone is used, then the device structure is simple, but measurement precision deteriorates due to false readings from dark hair and contaminants
Solution Approach 1:
The patent combines optical proximity sensor circuitry (infrared LED and photodiode) with electrical proximity sensor circuitry (capacitive electrodes) into a single integrated sensor system. The optical component detects reflected infrared light while the electrical component measures capacitive changes, and their outputs are merged to produce a unified proximity indication that overcomes the limitations of either component alone.
Solution Approach 2:
The integrated sensor system performs multiple sensing functions simultaneously - optical reflection detection and capacitive proximity detection - allowing the same sensor assembly to accurately detect proximity across different conditions (dark hair, contaminants, varying distances) that would defeat a single-type sensor.
2Reliability
If only infrared light-based sensing is used, then device complexity is low, but reliability deteriorates due to false positives and negatives
Solution Approach 1:
The patent merges optical sensing (infrared LED and photodiode) with electrical sensing (capacitive electrodes) into an integrated system where both sensing modalities operate simultaneously. The optical sensor detects reflected infrared light while the electrical sensor measures capacitive coupling changes, and their combined output provides reliable proximity detection that compensates for the weaknesses of each individual sensing method.
3Measurement precision
If optical sensing is used without electrical sensing, then manufacturing is simpler, but measurement precision worsens in challenging conditions
Solution Approach 1:
The patent integrates optical proximity sensor circuitry (infrared LED and photodiode) with electrical proximity sensor circuitry (coplanar or ring-shaped capacitive electrodes) into a single sensor assembly. This merged structure allows both optical and electrical sensing functions to be manufactured together as one unit, improving precision in challenging conditions while managing manufacturing complexity through integration.
4Measurement precision
If electrical sensing is added to optical sensing, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges optical proximity sensor circuitry with electrical proximity sensor circuitry into an integrated sensor system. The optical component (infrared LED and photodiode) and electrical component (capacitive electrodes) are combined in a single assembly with unified signal processing, achieving high measurement precision while managing complexity through integration rather than separate discrete components.
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 combination of sensing methods enhances the accuracy of proximity detection, reducing false readings caused by dark hair and contaminants, and ensures reliable operation of electronic devices by enabling appropriate mode changes based on user proximity.
Implementation Method 1
the light-emitting diode may emit infrared light outwards from the front face of the cellular telephone. When the cellular telephone is not in the vicinity of a user's head, the infrared light will not be reflected towards the light detector and only small amounts of reflected light will be detected by the light detector. When, however, the cellular telephone is adjacent to the user's head, the emitted light from the infrared light-emitting diode will be reflected from the user's head and detected by the light detector.
Implementation Method 2
The electrical proximity sensor circuitry may include at least first and second capacitive electrodes. The first and second capacitive electrodes may be coplanar conductive structures and/or ring-shaped conductive structures that laterally surround the optical proximity sensor circuitry.
Data Source
AI summary
An electronic device may be provided with a touch screen display that is controlled based on information from a proximity sensor. The proximity sensor may have a light source that emits infrared light and a light detector that detects reflected infrared light. When the electronic device is in the vicinity of a user's head, the proximity sensor may produce data indicative of the presence of the user's head. Variations in proximity sensor output due to user hair color and smudges on the proximity sensor can be accommodated by using an electrical sensing mechanism in addition to the light sensing mechanism. The proximity sensor may include a pair of capacitive electrodes for generating an electric field in the vicinity of the device. The presence of a user's head can sufficiently disturb the electric field so as to produce data indicative of the presence of the user's head.