Hall Sensor Bias Feedback Circuit for Lens Position Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The accuracy of optical image stabilization in camera modules is compromised due to variations in the output voltage of Hall sensors caused by external factors like temperature, leading to a degradation in the relationship between voltage output and position information.
Innovation Solution
An apparatus comprising a voltage-current conversion circuit and a current mirror circuit that adjusts the bias current of the Hall sensor, reducing voltage offset by generating a current that decreases with increasing input voltage and increases with decreasing input voltage, thereby stabilizing the bias current and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Hall sensor is used to measure position information, then position measurement capability is provided, but output voltage varies due to external factors like temperature causing measurement inaccuracy
Solution Approach 1:
The patent implements a feedback mechanism where the Hall sensor output voltage is continuously monitored, and when voltage variation exceeds a threshold (indicating temperature drift), a compensation current is automatically generated through the operational amplifier and transistor circuit to counteract the offset, thereby maintaining measurement accuracy despite external factor variations
Solution Approach 2:
The patent dynamically adjusts the bias current parameter supplied to the Hall sensor based on detected voltage variations. By changing the current parameter in response to temperature-induced voltage drift, the system compensates for sensor offset and maintains reliable position measurement accuracy
2Measurement precision
If the bias current of the Hall sensor is increased to improve signal strength, then measurement sensitivity improves, but voltage offset increases due to external factors
Solution Approach 1:
The patent converts the harmful effect of temperature-induced voltage offset into a beneficial compensation mechanism. The operational amplifier detects the offset voltage and generates a compensating current that flows through the Hall sensor, transforming the temperature drift problem into an opportunity for active offset cancellation and improved measurement reliability
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 apparatus effectively reduces the offset in Hall sensor output, enhancing the accuracy and stability of magnetic flux measurement, which improves the overall efficiency and precision of optical image stabilization in camera modules.
Implementation Method 1
A Hall sensor may be used to measure the position information of the lens module, and the Hall sensor may output a voltage varying depending on the position of the lens module
Implementation Method 2
The voltage-current conversion circuit is configured to generate a current configured to decrease when a voltage of an input terminal to which a bias current of a Hall sensor is input increases and increase when the voltage of the input terminal decreases
Implementation Method 3
The current mirror circuit has a current mirror structure configured to feedback the bias current based on the current generated by the voltage-current conversion circuit
Data Source
AI summary
An apparatus configured to reduce an offset of a Hall sensor includes a voltage-current conversion circuit and a current mirror circuit. The voltage-current conversion circuit is configured to generate a current configured to decrease when a voltage of an input terminal to which a bias current of a Hall sensor is input increases and increase when the voltage of the input terminal decreases. The current mirror circuit has a current mirror structure configured to feedback the bias current based on the current generated by the voltage-current conversion circuit.