LED Drive Circuit PWM Coordination for Image Capture
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Solution Overview
Problem
Current physical assessment devices, such as otoscopes and ophthalmoscopes, lack the capability to capture high-quality images of medical targets with appropriate illumination, often resulting in images with defects and artifacts that hinder medical professionals' use.
Innovation Solution
The integration of a physical assessment device with an LED illumination system using pulse width modulation (PWM) current for variable brightness, coupled with a smart device adapter that ensures consistent illumination during image capture, allowing for the attachment of a smartphone to capture images with reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PWM current is used to achieve variable LED brightness, then energy efficiency and brightness control are improved, but image capture quality deteriorates due to illumination discontinuity
Solution Approach 1:
The patent applies periodic action by using PWM (pulse width modulation) to control LED brightness through periodic switching. The drive circuit switches the LED on and off at high frequency, with the duty cycle determining the average brightness. This periodic illumination pattern enables energy-efficient variable brightness control while the coordination with image capture timing ensures quality images are obtained during the on-cycles.
Solution Approach 2:
The patent implements preliminary action by pre-coordinating the LED drive circuit with the image capture device timing. The system prepares the illumination timing in advance to ensure the LED is illuminated during the image capture period. This preliminary coordination prevents illumination discontinuity artifacts and ensures reliable image capture quality while maintaining PWM energy efficiency.
2Adaptability or versatility
If PWM current is used for variable LED brightness, then brightness control flexibility is improved, but image artifacts increase due to illumination discontinuity
Solution Approach 1:
The drive circuit uses periodic PWM switching to provide flexible brightness control while maintaining continuous illumination during image capture. By coordinating the PWM timing with the image capture device, the system ensures the LED remains illuminated during capture, eliminating banding and darkness artifacts while preserving brightness adjustability.
Solution Approach 2:
The system employs feedback coordination between the drive circuit and image capture device timing. The drive circuit receives timing information from the image capture device and adjusts its PWM output accordingly, ensuring illumination continuity during capture. This feedback mechanism eliminates artifacts while maintaining brightness control flexibility.
3Power
If LED brightness is varied using PWM, then illumination efficiency is improved, but diagnostic image quality deteriorates due to artifacts
Solution Approach 1:
The system performs preliminary coordination between the drive circuit and image capture device to ensure the LED is illuminated during capture. By preparing the illumination timing in advance and maintaining continuity during capture, the system preserves diagnostic image quality while utilizing PWM for efficient brightness control during non-capture periods.
Solution Approach 2:
The drive circuit uses feedback from the image capture device timing to adjust PWM output, ensuring illumination continuity during capture. This feedback coordination maintains high diagnostic image quality while preserving PWM illumination efficiency for brightness adjustment.
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
Enables the capture of high-quality images of medical targets with improved brightness control and reduced artifacts, enhancing diagnostic accuracy and usability for medical professionals.
Implementation Method 1
an illumination assembly including at least one LED and a drive circuit for powering the at least one LED with a pulse width modulation (PWM) current to achieve a variable brightness of the at least one LED
Data Source
Figure 1(a)
Figure 1(b)
Figure 2(a)
AI summary
A physical assessment device includes an instrument head, an optical assembly and an adapter interface member. The instrument head includes an illumination assembly including at least one LED and a drive circuit for powering the at least one LED with a pulse width modulation (PWM) current to achieve a variable brightness of the at least one LED. The optical assembly includes a plurality of optical components disposed along an optical axis. The adapter interface member enables an image capture device to be attached to the instrument head and aligned with the optical axis. The image capture device is configured to capture images of medical targets when illuminated by the at least one LED. The drive circuit is coordinated with the image capture device to ensure that the medical targets are at least partially illuminated during the capturing of the images notwithstanding the variable brightness of the at least one LED.