Current Recycling VCM Driver Circuit for Power Reduction
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Solution Overview
Problem
Existing driver circuits for voice coil motors (VCMs) in optical image stabilization (OIS) mechanisms of compact camera modules consume excessive power due to separate current sources for each VCM, which is inefficient, especially in portable devices with limited voltage supply.
Innovation Solution
Implementing a current recycling technique where a portion of the coil current from the VCM with higher demand is routed through the VCM with lower demand, using a network of switches and current sources controlled by a driver controller to achieve this recycling, and switching to an independent mode when voltage compliance is insufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate current sources are used for each VCM coil, then each coil can be independently controlled, but power consumption increases
Solution Approach 1:
The patent merges the two separate current sources into a single shared current source that can supply current to either VCM coil independently or to both coils simultaneously through a switching network, thereby reducing total power consumption while maintaining independent control capability
Solution Approach 2:
The single current source is designed to serve multiple functions: it can supply current to the first VCM coil, the second VCM coil, or both coils simultaneously depending on the switching configuration, replacing the need for two dedicated current sources
2Use of energy by moving object
If a single current source is shared between two VCMs, then power consumption is reduced, but voltage compliance becomes insufficient under high current demands
Solution Approach 1:
The patent implements dynamic switching between two operating modes: a power-saving mode where a single current source supplies one coil at a time, and a high-performance mode where two independent current sources are activated when voltage compliance is insufficient, allowing the system to adapt to varying current demand conditions
Solution Approach 2:
The system changes the operational parameters by switching between different current source configurations based on the magnitude of current demanded by the VCMs, transitioning from a single current source configuration to a dual current source configuration when voltage compliance requirements cannot be met
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 approach reduces power consumption by recycling current between VCMs, minimizing heat generation and extending battery life in portable devices, while ensuring stable operation even under high current demands.
Implementation Method 1
The displacement in these X and Y directions are proportional to the current through their respective VCM coils
Data Source
AI summary
A method for driving first and second voice coil motors (VCMs) by generating a first coil current through the first VCM and routing a portion (not all) of the first coil current through the second VCM when a first VCM movement command is commanding greater movement than a second VCM movement command. A second coil current is generated through the second VCM and a portion (not all) of the second coil current is routed through the first VCM, when the first VCM movement command is commanding smaller movement than the second VCM movement command. This may reduce power consumption. Other embodiments are also described and claimed.