Camera Screening Component for PWM Interference
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Solution Overview
Problem
PWM drive signals used for electro-mechanical actuators in cameras, particularly those with shape memory alloy (SMA) materials, cause interference with image sensors, leading to artefacts like horizontal lines or speckle in digital images, and existing solutions that switch between PWM and linear drive circuits increase cost and complexity.
Innovation Solution
A camera design featuring a screening component made of magnetically permeable or electrically conductive materials, electrically isolated from the actuator and image sensor, which reduces interference from PWM drive signals without additional cost or complexity, including configurations with multiple layers and insulating materials to enhance screening efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PWM drive signal is used to drive the actuator, then power efficiency is improved, but image quality deteriorates due to interference artefacts
Solution Approach 1:
A screening component is introduced as an intermediary element positioned between the actuator and the image sensor. This screening component, made of magnetically permeable or electrically conductive material, acts as a mediator that blocks or shields the electromagnetic interference from the PWM drive signal while allowing the actuator to continue driving the lens. The screening component effectively separates the noise source from the sensitive sensor without requiring changes to the PWM drive system itself.
2Object-affected harmful factors
If dual drive circuits (PWM and linear) are used to reduce noise, then image quality is improved, but device complexity and cost increase
Solution Approach 1:
The harmful electromagnetic interference is extracted and isolated from the main system by introducing a dedicated screening component. Instead of modifying the complex dual-drive circuit approach, the solution extracts the noise problem and contains it within the screening component, allowing the simple PWM drive circuit to continue operating while the screening component handles the interference mitigation.
3Object-affected harmful factors
If screening component is electrically connected to earth, then shielding effectiveness is improved, but manufacturing difficulty increases due to earthing requirements
Solution Approach 1:
The screening component is designed as a simple, standalone element that does not require complex earthing infrastructure. By using materials with inherent shielding properties (magnetically permeable or electrically conductive materials) and positioning the component strategically between the actuator and sensor, effective noise reduction is achieved without the need for elaborate earthing systems, simplifying manufacturing and assembly.
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 effectively minimizes image noise and artefacts by confining the electromagnetic field within the screening component, maintaining power efficiency and compact design, even without electrical earthing, thereby improving image quality.
Implementation Method 1
a screening component located between the conductive components of the actuator and the image sensor, the screening component being electrically isolated from the actuator and the screening component being configured to reduce interference from the PWM drive signal with the image sensor
Implementation Method 2
The screening component may comprise magnetically permeable material, for example having a high relative magnetic permeability
Implementation Method 3
The screening component may comprise electrically conductive material, for example having a high electrical conductivity
Data Source
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AI summary
A miniature camera comprises: an image sensor; an actuator which includes conductive components capable of conducting a pulse width modulation drive signal for driving the actuator; and a screening component located between (a) the conductive components of the actuator and (b) the image sensor, the screening component being electrically isolated from the actuator.