Lens Actuator Sensing Coils for Miniature Camera Displacement Detection
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Solution Overview
Problem
Existing voice coil motor (VCM) technology is difficult to apply to subminiature, low-power camera modules, particularly in smartphones, due to the need for increased resolution and miniaturization, requiring improved sensitivity and accuracy in lens displacement detection.
Innovation Solution
A lens moving apparatus with a bobbin, coil, magnet, and sensing coils, utilizing elastic members and terminals for enhanced induction voltage output, allowing precise control of lens movement through AC and DC drive signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voice coil motor (VCM) technology is applied to camera modules, then lens displacement control is achieved, but sensitivity and accuracy of displacement detection deteriorate in miniaturized designs
Solution Approach 1:
The sensing system is divided into multiple independent sensing coils positioned at different locations (first sensing coil at the housing, second sensing coil at the base). Each sensing coil independently detects displacement, and their outputs are combined to achieve high-precision measurement without requiring a large single sensing element, thus maintaining detection sensitivity while accommodating miniaturization.
Solution Approach 2:
The patent transitions from single-point displacement detection to multi-point spatial detection by positioning sensing coils at different locations and orientations. This dimensional expansion of the sensing approach enables accurate displacement measurement in a compact volume by utilizing spatial distribution of sensing elements rather than relying on a single large sensing component.
2Manufacturing precision
If camera resolution is increased, then image quality improves, but lens actuator size increases
Solution Approach 1:
The patent replaces traditional mechanical displacement sensing mechanisms with electromagnetic induction-based sensing coils. This substitution eliminates the need for complex mechanical feedback systems and large actuator components, enabling high-resolution camera modules to maintain compact lens actuator sizes while achieving precise control through electrical sensing and control.
3Measurement precision
If single sensing coil is used, then device complexity is low, but measurement precision deteriorates
Solution Approach 1:
The patent merges the output signals from multiple sensing coils through terminal connections to achieve enhanced measurement precision. By combining the electrical outputs of the first and second sensing coils at designated terminals, the system achieves accurate displacement detection through signal integration, managing the complexity of multiple sensors through systematic electrical connection and processing.
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
Improves sensitivity and accuracy in detecting bobbin displacement, enabling high-resolution camera functions such as autofocusing and zooming in miniaturized camera modules.
Implementation Method 1
a coil coupled to the bobbin, a magnet, which is disposed at the housing so as to face the coil
Implementation Method 2
a first sensing coil, which is disposed at the housing and generates a first induction voltage through interaction with the coil
Implementation Method 3
a second sensing coil, which is disposed at the base and generates a second induction voltage through interaction with the coil
Data Source
AI summary
A lens moving apparatus including a base, a bobbin located above the base and configured to be movable in an optical axis direction, a first terminal, a second terminal, a third terminal and a fourth terminal which are coupled to the base and spaced apart from each other; and a coil comprising a first end connected to the third terminal and a second end connected to the fourth terminal. The base includes a first projection and a second projection which are spaced apart from each other. The first terminal comprises a first portion exposed from an upper surface of the first projection of the base, and the second terminal comprises a second portion exposed from an upper surface of the second projection of the base.