Voice Coil Motor Driving Circuit Miniaturization
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Solution Overview
Problem
Existing driving apparatuses for voice coil motors in camera modules face challenges in miniaturization due to the need for separate transistors and resistors, which affects precise control of the motor current and area efficiency.
Innovation Solution
A driving apparatus is designed with a signal generator to create path and current signals, a controller to generate control signals based on these signals, and a driving circuit unit using transistors to form the driving current path, allowing for precise control of the voice coil motor by mirroring a reference current and maintaining potential differences across transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If separate transistors and resistors are used for detecting voltage and controlling current in the H bridge circuit, then the voice coil motor can be controlled, but the area of the actuator increases and miniaturization is hindered
Solution Approach 1:
The patent combines the functions of separate transistors and resistors into integrated transistor structures within the H bridge circuit. The control circuit uses transistors that perform both switching and current detection functions, eliminating the need for separate detection components and reducing overall circuit area while maintaining control capability.
Solution Approach 2:
The transistors in the H bridge circuit are designed to serve multiple functions simultaneously: they act as switching elements for bidirectional current control, current detection sensors, and signal amplification devices. This multi-functionality reduces the total component count and enables actuator miniaturization without sacrificing control precision.
2Area of stationary object
If separate transistors and resistors are removed for miniaturization, then actuator area decreases, but precise control of voice coil motor current becomes difficult
Solution Approach 1:
The control circuit incorporates feedback mechanisms where the same transistors used for switching also provide current detection feedback. The circuit monitors the actual current flowing through the voice coil motor and adjusts the control signals accordingly, ensuring precise current control even with integrated transistor structures that eliminate separate detection components.
Solution Approach 2:
The patent replaces traditional separate physical components (discrete transistors and resistors) with integrated transistor structures that combine multiple functions. This substitution maintains control precision through sophisticated circuit design and control algorithms while reducing the physical area occupied by the actuator components.
3Ease of manufacture
If the H bridge circuit is simplified by removing separate components, then manufacturing becomes easier and area is reduced, but control accuracy may be compromised
Solution Approach 1:
By merging multiple functions into integrated transistor structures, the patent reduces the number of discrete components that need to be assembled and connected, simplifying the manufacturing process. The integrated design eliminates connection points between separate components, reducing assembly complexity and potential failure points while maintaining control reliability through careful circuit design.
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 enables precise control of the voice coil motor while allowing for the miniaturization of the camera module actuator, independent of the motor load, by removing the need for separate transistors and resistors, thus enhancing area efficiency and control accuracy.
Implementation Method 1
a voice coil motor that applies electromagnetic force to a magnet in order to provide driving force for the lens barrel to move in the optical axis direction
Data Source
AI summary
A driving apparatus for a voice coil motor includes a signal generator configured to generate a path signal determining a path of a driving current provided to the voice coil motor and a current signal determining a level of the driving current, a controller configured to generate a control signal by comparing a reference current determined by the current signal, with the driving current flowing in the voice coil motor, and a driving circuit unit including transistors connected to the voice coil motor, the transistors being configured to form the path of the driving current by performing a switching operation based on the path signal and the control signal.