Motor Driving Circuit Stepwise Current Control
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Solution Overview
Problem
Existing motor driving circuits for voice coil motors, used in camera auto-focus functions, face challenges in rapidly changing current amounts, leading to increased vibration and prolonged stabilization time, and require significant processing load to achieve gradual current changes.
Innovation Solution
A motor driving circuit that includes a comparator and a current control signal update circuit to control the current flowing through the motor coil in a stepwise manner, allowing the current to be adjusted to a set value without continuous microcomputer processing, using a comparator to output comparison signals and a current control signal update circuit to update the current control signal based on these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the current amount of the voice coil motor is rapidly changed to achieve a desired position, then the response speed is improved, but vibration is increased and stabilization time is prolonged
Solution Approach 1:
The current control signal update circuit divides the current change process into multiple discrete steps. Instead of rapidly changing the current in one step, the circuit segments the change into incremental adjustments, where each step moves the current closer to the target value. This segmentation reduces vibration at each step while maintaining overall fast response through efficient step sequencing.
2Object-affected harmful factors
If the current amount is changed gradually to reduce vibration, then stabilization is improved, but processing load on the microcomputer increases
Solution Approach 1:
The invention extracts the complex processing logic from the microcomputer and relocates it to a dedicated current control signal update circuit. This circuit autonomously generates the stepped current control signals based on simple comparison results from a comparator, eliminating the need for the microcomputer to perform complex gradual adjustment calculations. The microcomputer only needs to output the target current value, significantly reducing its processing load.
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 reduces processing load on the microcomputer and minimizes vibration by allowing the current to be adjusted efficiently in a stepwise manner, stabilizing the lens position quickly while reducing noise and power consumption.
Implementation Method 1
a comparator configured to output a comparison signal indicating a comparison result between a set current amount and a current amount based on an inputted set current signal according to the set current amount and a current signal according to the current amount flowing through the motor coil
Implementation Method 2
A voice coil motor is often used as a motor for realizing an auto-focus function of a camera incorporated in a cellular phone. The voice coil motor is a motor in which a movement amount is changed according to a current amount
Data Source
AI summary
A motor driving circuit for controlling a current amount flowing through a motor coil includes: a comparator configured to output a comparison signal indicating a comparison result between a set current amount and a current amount based on an inputted set current signal according to the set current amount and a current signal according to the current amount flowing through the motor coil; a current control signal update circuit configured to update a current control signal for controlling the current amount flowing through the motor coil in a stepwise manner so that the current amount flowing through the motor coil is changed to the set current amount in a stepwise manner, based on the comparison signal outputted from the comparator; and a driving circuit configured to drive the motor coil based on the current control signal outputted from the current control signal update circuit.