Voice Coil Motor Drive Circuit Gravity Offset Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Voice coil motor systems in electronic devices, such as smartphones and cameras, face challenges in stabilizing the focusing lens at an optimum position quickly and efficiently, especially when the device's posture changes, leading to increased power consumption and prolonged stabilization times due to the influence of gravity.
Innovation Solution
A drive circuit that receives signals for the target position and the device's posture, generating a current command value to offset the effect of gravity, allowing the voice coil motor to converge to the target position rapidly by behaving as if gravity does not affect it, with the offset component defined by Gx/(2πf0)^2, where f0 is the resonance frequency and Gx is the gravity component in the stroke direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the drive circuit does not compensate for gravity influence, then the device structure remains simple, but the feedback control time increases and power consumption increases
Solution Approach 1:
The drive circuit performs preliminary compensation for gravity influence by adding an offset component based on posture information before the feedback control loop operates. This preliminary action pre-adjusts the current command value to counteract gravity's effect, allowing the feedback control to converge faster without requiring complex real-time adjustments during the control loop.
Solution Approach 2:
The patent introduces posture information as an intermediary element that mediates between the target position signal and the current command value. This intermediary provides the drive circuit with knowledge about gravity's influence direction and magnitude, enabling it to pre-compensate without requiring complex mechanical structures or additional actuators.
2Device complexity
If the drive circuit does not compensate for gravity influence, then the circuit design remains simple, but power consumption increases due to prolonged stabilization
Solution Approach 1:
By performing gravity compensation in advance through the offset component calculation, the system reaches the target position faster, reducing the duration of feedback control operations and thereby lowering overall power consumption without requiring energy-intensive mechanical counterweights or additional compensation mechanisms.
3Loss of time
If gravity compensation is implemented, then the stabilization time decreases, but the drive circuit complexity increases
Solution Approach 1:
The patent uses posture information as a simple intermediary that can be obtained from existing sensors (like accelerometers in mobile devices) without adding complex mechanical structures. The compensation calculation involves basic arithmetic operations (multiplication and addition) that can be implemented with simple circuitry, achieving fast stabilization with minimal increase in circuit complexity.
Solution Approach 2:
The system changes the parameter of the current command value by adding an offset component that depends on posture parameters. This parameter adjustment approach allows the same drive circuit to adapt to different postures and gravity conditions without requiring structural changes or additional hardware components.
4Productivity
If gravity compensation is implemented, then the camera can reach shooting-ready state quickly, but the drive circuit requires additional processing
Solution Approach 1:
The drive circuit performs the gravity compensation calculation in advance as part of the current command value generation process. By incorporating the offset component calculation into the existing control loop, the system achieves fast shooting-ready status without requiring separate, complex post-processing steps or additional control loops.
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 shortens the feedback control time, reduces power consumption, and enables the camera to reach a shooting-ready state quickly, independent of the device's posture, thereby facilitating timely shots and extending battery life in portable devices.
Implementation Method 1
A VCM can generate a driving force according to the direction of a current flowing through a coil
Implementation Method 2
a force of a spring attached to a mover of the VCM
Implementation Method 3
gravity acts on the lens 520 in the same direction (indicated by an arrow g) as the stroke direction 524
Data Source
AI summary
A drive circuit, which is mounted on an electronic apparatus having a voice coil motor and drives the voice coil motor, includes: an interface circuit configured to receive a first signal indicating a target position of the voice coil motor and a second signal related to a posture of the electronic apparatus; a control circuit configured to generate a current command value of a drive current in response to the first signal and the second signal; and a current driver configured to generate the drive current in response to the current command value and supply the drive current to the voice coil motor.