Hall Sensor Front-End Circuit for Temperature-Stable OIS Sensing
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Solution Overview
Problem
Camera modules in mobile devices face challenges in maintaining accurate sensing signals from hall sensors due to temperature and offset changes, which affect the optical image stabilization (OIS) functionality and shake correction performance.
Innovation Solution
An analog front-end circuit with a hall bias correction loop and an offset correction loop, along with a temperature sensor, is implemented to automatically adjust the hall bias current and offset correction voltage, ensuring accurate sensing voltage and position correction of the hall sensors, even with temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature changes occur during camera module operation, then the sensing voltage and offset of the hall sensor change, but this leads to inaccurate position sensing and degraded OIS performance
Solution Approach 1:
The patent implements a feedback mechanism where the hall sensor continuously monitors the position of the actuator, and the controller adjusts the actuator position based on the sensed feedback signal. This closed-loop system compensates for temperature-induced drift by continuously correcting the position based on real-time sensing data, thereby maintaining sensing accuracy despite temperature changes.
Solution Approach 2:
The patent employs parameter changes by adjusting the bias voltage or operating parameters of the hall sensor based on detected temperature changes or offset drift. The controller modifies electrical parameters (such as bias current or reference voltage) to compensate for temperature-induced variations in the hall sensor's output characteristics, thereby maintaining accurate position sensing across different temperature conditions.
2Adaptability or versatility
If the hall sensor operates over a wide temperature range, then the camera module is more versatile, but the sensing voltage and offset drift due to temperature changes
Solution Approach 1:
The feedback mechanism continuously monitors the actuator position through the hall sensor and adjusts the system response based on the sensed position. This real-time feedback allows the system to maintain precise position sensing across a wide temperature range by compensating for temperature-induced offset drift through continuous correction based on actual position feedback.
Solution Approach 2:
The patent implements dynamic compensation where the controller actively adjusts operating parameters or correction values based on real-time temperature conditions or sensed position data. This dynamic adaptation allows the system to maintain measurement precision across varying temperature conditions by continuously optimizing the sensing and correction parameters rather than using fixed static values.
3Device complexity
If no temperature compensation is implemented, then the device complexity is reduced, but the OIS control accuracy deteriorates under temperature variations
Solution Approach 1:
The feedback-based compensation mechanism uses the existing hall sensor and controller to continuously monitor and correct position sensing errors. By utilizing the already-present feedback infrastructure of the OIS system, the patent achieves temperature compensation without adding significant circuit complexity, as the correction is performed through software or control logic rather than additional hardware components.
Solution Approach 2:
The system performs self-compensation by using its own sensing resources (the hall sensor) to detect and correct its own temperature-induced errors. The controller utilizes the position feedback signal to identify offset drift and automatically adjusts the actuator control or sensing parameters to compensate for temperature effects, enabling the system to correct its own errors without external intervention or complex additional circuitry.
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 effectively stabilizes the camera module by accurately correcting sensing voltage and offset changes, enhancing the OIS functionality and preventing hand shake-induced image blur, regardless of temperature fluctuations.
Implementation Method 1
The OIS control driver senses the position of an actuator through a hall sensor
Data Source
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AI summary
An analog front-end circuit includes a hall bias correction loop circuit configured to correct a sensing voltage of a hall sensor by adjusting a hall bias current flowing in the hall sensor while tracking a change in the sensing volage of the hall sensor based on a temperature change, an offset correction loop circuit configured to correct an offset correction voltage while tracking an offset change of the hall sensor and an offset change of an amplifier circuit based on the temperature change, the amplifier circuit configured to amplify and output the sensing voltage of the hall sensor, corrected through at least one of the hall bias correction loop circuit and the offset correction loop circuit, and an analog-digital converter configured to convert an output voltage of the amplifier circuit into sensing data and output the sensing data.