Lens Driving Apparatus Temperature Correction for Focus Stability
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Solution Overview
Problem
Optical modules in digital cameras and mobile devices face focus position deviations due to thermal expansion and contraction, leading to unstable autofocus and camera shake correction, even with feedback control, as ambient temperature changes affect the lens position and focal distance.
Innovation Solution
A driving apparatus that includes an actuator, magnetic field detection section, and control section, which corrects the driving amount based on temperature information to adjust the lens position accurately, using temperature detection and magnetic field correction to maintain focus despite temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is performed to move the lens to a target position, then the lens position control accuracy is improved, but focus position deviation occurs due to thermal expansion and contraction of the lens and lens holder
Solution Approach 1:
The patent changes the parameter being controlled from absolute lens position to relative position that compensates for thermal effects. The correction section adjusts the driving amount based on temperature information, effectively changing the control parameter to account for thermal expansion and contraction, thereby maintaining focus position stability despite temperature variations.
Solution Approach 2:
The patent introduces a feedback mechanism where temperature information is detected and used to correct the driving amount of the actuator. The correction section receives temperature information and feed it back to adjust the lens driving operation, creating a closed-loop control system that compensates for thermal effects on focus position.
2Measurement precision
If the lens is moved to a target position by feedback control, then the lens position accuracy is improved, but the effective focal distance changes with temperature causing focus deviation
Solution Approach 1:
The patent changes the control approach by introducing temperature as an additional parameter that affects the driving amount. Instead of controlling only the lens position, the system now controls the lens position while compensating for temperature-induced changes in effective focal distance, thereby maintaining focus accuracy across varying temperatures.
3Reliability
If temperature correction is applied to the driving amount, then focus position stability is improved, but the device complexity increases due to additional correction section
Solution Approach 1:
The patent merges the temperature correction function with the existing lens driving control system. The correction section is integrated into the control flow, receiving temperature information and combining it with the target position information to generate the corrected driving amount, thereby reducing overall system complexity compared to having separate independent correction and control systems.
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 stabilizes the focus position and reduces focus deviations by accurately positioning the lens, ensuring effective autofocus and camera shake correction even with temperature fluctuations.
Implementation Method 1
an actuator that changes a relative position between a lens section and an imaging device
Implementation Method 2
a magnetic field detection section that detects magnetic field information corresponding to the position of the lens section
Implementation Method 3
the position of the lens varies with thermal expansion and thermal contraction of the lens, a lens holder and the like
Data Source
AI summary
An optical module that stably operates an optical camera shake correction, an autofocus function and the like even if a temperature change occurs; a driving apparatus including an actuator that changes a relative position between a lens section and an imaging device, a correction section that corrects a driving amount of the actuator according to temperature information showing an ambient temperature of the lens section, and a control section that controls the driving amount of the actuator; a lens unit, a device, a correction method, and a computer readable recording medium are provided.