Liquid Lens Control Circuit for Compact Camera Modules
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Solution Overview
Problem
Existing camera modules with liquid lenses face challenges in accurately controlling the focal distance and interface movement due to high power consumption and size constraints, particularly in implementing auto-focusing and optical image stabilization functions without increasing the device's thickness.
Innovation Solution
A camera module with a liquid lens that includes a common electrode and individual electrodes, a voltage control circuit, and a capacitance measuring circuit to accurately measure and control the interface movement by recognizing capacitance variations, allowing for efficient optical stabilization and reduced size through the use of a feedback circuit and lower voltage capacitance measuring feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a liquid lens with high voltage (30V-50V) is used to achieve accurate focal distance adjustment, then the measurement precision of interface position is improved, but the power consumption increases and the capacitance measurement becomes difficult
Solution Approach 1:
The patent applies periodic action by using a falling-edge state timing for capacitance measurement. The control module measures capacitance during the falling edge of the voltage signal (when voltage transitions from high to low), rather than during continuous high voltage operation. This periodic measurement approach reduces power consumption while maintaining measurement precision, as the capacitance is measured briefly during voltage transitions rather than continuously during high-voltage operation.
2Measurement precision
If a feedback circuit is added to measure capacitance and control interface movement, then the measurement precision and control accuracy are improved, but the device complexity increases
Solution Approach 1:
The patent merges the voltage control function and capacitance measurement function into a single integrated control module. The control module includes both a voltage control unit that generates driving voltages and a capacitance measuring unit that measures capacitance between electrodes. By combining these functions in one module rather than using separate circuits, the patent reduces overall device complexity while maintaining measurement precision.
Solution Approach 2:
The patent implements feedback control by using the measured capacitance values to adjust and control the liquid lens interface position. The control module measures capacitance between the common electrode and individual electrodes, then uses this feedback information to control the focal distance and interface movement. This feedback mechanism improves measurement precision and control accuracy without requiring overly complex external measurement systems.
3Volume of moving object
If the camera module size is reduced by using a liquid lens, then the volume is decreased, but the power consumption increases due to high voltage requirements
Solution Approach 1:
The patent reduces power consumption in the compact camera module by implementing periodic capacitance measurement during falling-edge voltage transitions. Instead of continuously measuring capacitance or maintaining high voltage for measurement purposes, the system briefly measures capacitance during natural voltage transitions, significantly reducing energy consumption while maintaining the compact form factor enabled by the liquid lens.
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 enables more accurate measurement and control of the liquid lens interface, enhancing image quality and reducing power consumption, thereby improving optical stabilization and camera module efficiency while maintaining a compact size.
Implementation Method 1
a capacitance measuring circuit to measure a capacitance between the common electrode and the individual electrodes
Implementation Method 2
a liquid lens, which performs auto-focusing and anti-handshaking functions by electrically adjusting the curvature of an interface of two types of liquids
Data Source
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AI summary
The present invention provides a liquid lens control circuit comprising: a liquid lens comprising a plurality of individual electrodes arranged at separate regions on a same level, and a common electrode arranged on a different level from the level on which the plurality of individual electrodes are arranged; a voltage control circuit for supplying a voltage via the common electrode and at least one of the plurality of individual electrodes in the liquid lens in order to control an interface of the liquid lens; and a capacitance measuring circuit for calculating the capacitance between the common electrode and at least one of the plurality of individual electrodes in the liquid lens by using a switched capacitor.