Piezoelectric Lens Module Friction Control for Gravity Speed Difference
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Solution Overview
Problem
Piezoelectric motor-driven lens modules experience significant speed differences during zooming or focusing due to gravity, leading to instability and increased circuit complexity and cost, as the frictional force between the motor and lens module is not constant, resulting in slower upward movement compared to downward movement.
Innovation Solution
A piezoelectric driving module with a housing, a piezo member, a rubbing element, and a guiding mechanism that generates a predetermined frictional force to reduce gravity-induced speed differences, ensuring consistent movement by adjusting the ratio of speeds in both directions to within 1:1.3, using a pre-pressing element and position detection module for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a piezoelectric motor is used to drive the lens module, then the size, power consumption, and complexity of the driving structure are reduced, but a speed difference occurs between upward and downward movement due to gravity
Solution Approach 1:
The rubbing element generates a frictional force that acts as a counterbalancing force to gravity. When the lens module moves upward, the frictional force from the rubbing element assists the piezoelectric motor by providing an additional upward force. When moving downward, the frictional force opposes gravity. This counteracts the gravitational effect that causes speed differences, making the upward and downward movement speeds more consistent.
2Speed
If the piezoelectric motor drives the lens module vertically upward against gravity, then focusing or zooming is achieved, but the movement speed is slower compared to downward movement
Solution Approach 1:
The rubbing element serves as an intermediary between the lens module and the housing. It generates a frictional force that is transferred to the lens module during movement. This intermediary frictional force compensates for the gravitational force acting on the lens module, thereby reducing the speed difference between upward and downward movements and making the actuating force more consistent throughout the driving process.
3Reliability
If a precision driving element and large number of transmission elements are used, then the lens module can be driven reliably, but the size, complexity, and cost of the mechanical structure increase
Solution Approach 1:
The invention extracts and eliminates the need for complex transmission elements (gears, belts, linkages) by using the piezoelectric motor to directly drive the lens module through friction contact with the rubbing element. This direct-drive approach removes unnecessary intermediate transmission components, simplifying the mechanical structure while maintaining reliable driving functionality.
Solution Approach 2:
The invention replaces the traditional mechanical transmission system (precision driving elements with multiple transmission components) with a piezoelectric-based direct drive system. The piezoelectric motor converts electrical energy directly into mechanical motion through piezoelectric deformation, eliminating the need for complex mechanical transmission elements and reducing overall system complexity.
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
The solution stabilizes the lens module's movement by maintaining a consistent frictional force, reducing speed differences and enhancing precise control, thereby improving image quality and reducing the complexity and cost of the positioning module.
Implementation Method 1
a piezoelectric motor produces a piezoelectric effect, which is a reversible process and can be divided into a 'direct piezoelectric effect', which refers to the generation of voltage by the piezoelectric motor due to a volume change of the motor material, and a 'converse piezoelectric effect', which refers to a volume change of the motor material triggered by an applied voltage
Implementation Method 2
a predetermined frictional force is generated between the rubbing element and the lens module to reduce a gravity-induced speed difference of the lens module
Data Source
AI summary
A piezoelectric driving module for lens, which defines a photographic optical axis and includes a housing, a driven object (e.g., a lens module), a piezo member, and a rubbing element. The piezo member and the rubbing element are provided in the housing and located on two lateral sides of the driven object respectively. The piezo member drives the driven object by friction so that the driven object can be moved along the photographic optical axis until focused. Meanwhile, a predetermined frictional force is generated between the rubbing element and the driven object to reduce a gravity-induced speed difference between forward and backward movements of the driven object along the photographic optical axis.