Inductorless Electroactive Lens Driver Using Capacitive Charge Pump
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Solution Overview
Problem
Conventional optical systems for camera modules, such as those in cell phones, are limited by space constraints, making it impossible to incorporate mechanical focusing or optical zoom, and existing electroactive lens drivers require external inductors or transformers that occupy valuable space.
Innovation Solution
An inductorless and transformerless system using a capacitive charge pump circuit to generate a high voltage DC supply from a low voltage source, which is then converted to a high AC voltage to drive an electroactive lens, eliminating the need for external components like inductors and transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional optical systems with mechanical focusing are used, then focusing capability is achieved, but space requirements are not met
Solution Approach 1:
The patent replaces the mechanical focusing system with an electroactive lens that uses electrical fields to change focal length. The electroactive lens element responds to applied voltage by changing its shape or refractive index, enabling focusing without any mechanical moving parts. This substitution eliminates the need for space-consuming mechanical components while maintaining focusing capability.
Solution Approach 2:
The electroactive lens changes its optical parameters (focal length) by applying different voltage levels. By varying the electrical parameter (voltage), the lens dynamically adjusts its focusing properties without physical repositioning. This allows compact integration while preserving full focusing functionality through electrical control rather than mechanical adjustment.
2Power
If external inductors or transformers are used in the lens driver, then high voltage generation is achieved, but device size increases
Solution Approach 1:
The patent integrates the high voltage generation functionality directly into the lens driver IC by incorporating a charge pump circuit. This merges the voltage multiplication function with the existing driver circuitry, eliminating the need for separate external inductors or transformers. The charge pump uses only small capacitors that can be implemented on-chip or as minimal external components, dramatically reducing overall driver size while maintaining high voltage output capability.
3Area of stationary object
If a compact integrated driver is used, then space is reduced, but design complexity increases
Solution Approach 1:
The patent uses a charge pump circuit as an intermediary mechanism to generate high voltage from the low voltage supply. This charge pump serves as a compact voltage multiplication stage that can be easily integrated into the driver IC. By using this well-established circuit topology with simple capacitive elements, the design achieves high voltage generation without requiring complex transformer or inductor-based solutions, thus managing design complexity while maintaining compactness.
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 allows for a compact, integrated electroactive lens driver that fits within the camera module, enabling focusing and zoom capabilities without the size limitations of conventional systems, while reducing design complexity and increasing efficiency.
Implementation Method 1
a capacitive charge pump circuit to generate a high voltage DC supply from a low voltage source
Implementation Method 2
An electroactive lens is a single optical lens element that changes its focal length in response to an applied voltage
Data Source
AI summary
An electroactive lens driver comprises a voltage generator generating a high alternating current voltage signal for application to an electroactive lens in response to a low direct current voltage signal. The voltage generator does not include an inductor or a transformer.