Hall Sensor Position Detection with Temperature Compensation
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Solution Overview
Problem
Camera module actuators, such as autofocus (AF), optical image stabilization (OIS), and iris (IRIS) actuators, face challenges in accurately detecting object positions due to variations in hall voltage caused by temperature changes, affecting the precision of position detection.
Innovation Solution
A position detection device comprising a first and second hall element, a differential amplifier, a summing amplifier, a comparer, and a current converter, which generates a sum voltage to accurately detect object positions by compensating for temperature-induced hall voltage variations, using a feedback loop to adjust the bias current based on error voltage calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hall elements are used to detect position in camera module actuators, then position detection function is enabled, but detection accuracy deteriorates due to temperature-induced hall voltage variations
Solution Approach 1:
The patent implements a feedback mechanism where the detected position information is used to adjust the bias current through a current converter. The system continuously monitors the hall voltage and compensates for temperature-induced variations by adjusting the bias current, thereby maintaining accurate position detection across different temperature conditions.
Solution Approach 2:
The patent changes the operating parameter (bias current) of the hall elements based on temperature conditions. By dynamically adjusting the bias current through the current converter according to the detected position and temperature effects, the system compensates for hall voltage variations and maintains detection accuracy.
2Measurement precision
If temperature compensation is implemented to maintain hall voltage stability, then position detection accuracy improves, but device complexity increases due to additional circuit components
Solution Approach 1:
The patent combines multiple functions into integrated circuit components. The differential amplifier simultaneously processes signals from multiple hall elements, the summing amplifier combines the differential output with bias current feedback, and the current converter integrates position detection with bias current adjustment. This merging reduces the number of separate components while achieving temperature compensation.
Solution Approach 2:
The circuit components perform multiple functions: the differential amplifier both compares hall voltages and provides signal conditioning, the summing amplifier both combines signals and implements feedback, and the current converter both detects position and adjusts bias current. This multi-functionality reduces overall circuit complexity while maintaining compensation capability.
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
The solution ensures precise position detection of camera module components, improving the accuracy and stability of autofocus, optical image stabilization, and iris functions by effectively compensating for temperature-related hall voltage changes, thereby enhancing image quality and reducing shaking-related blurriness.
Implementation Method 1
A hall voltage of the hall element, however, varies as temperature changes. Thus, it may be necessary to compensate for changes in hall voltage caused by changes in temperature to accurately detect a position of the detection object
Data Source
AI summary
A device with position detection includes: a first hall element; a second hall element; a differential amplifier configured to generate a subtraction voltage by differentially amplifying a first hall voltage generated by the first hall element and a second hall voltage generated by the second hall element; a summing amplifier configured to generate a sum voltage by summatively amplifying the first and second hall voltages; a comparer configured to compare a reference voltage with the subtraction voltage to generate an error voltage; and a current converter configured to generate a bias current provided to the first and second hall elements, based on the error voltage, wherein the device is configured to detect a position of a detection object based on the sum voltage.