LED Illumination Control for Image Measuring Devices
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Solution Overview
Problem
High-brightness LEDs struggle with maintaining constant brightness in low-brightness lighting due to instability with small currents, and achieving accurate stroboscopic illumination is challenging due to inconsistencies in lighting intervals and periods, which affects image quality in image measuring devices.
Innovation Solution
The method involves switching the driving circuits of a common high-brightness LED between pseudo-continuous illumination and stroboscopic illumination by altering the lighting cycle, using a pulse lighting circuit for reduced brightness and a stroboscopic or continuous lighting circuit for high-brightness emission, allowing for accurate brightness and timing control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a high-brightness LED is driven with small current for low-brightness continuous illumination, then power consumption is reduced, but brightness stability deteriorates
Solution Approach 1:
The patent applies periodic action by using pulse lighting instead of continuous low-current operation. The LED is illuminated in periodic pulses with appropriate duty cycle, which maintains brightness stability while achieving low-brightness effect. This resolves the contradiction by replacing continuous small current operation with periodic operation that keeps the LED in its stable high-current operating region.
2Productivity
If stroboscopic illumination is used for non-stop measuring mode, then measurement throughput is improved, but lighting interval consistency deteriorates
Solution Approach 1:
The patent employs feedback control to maintain consistent lighting intervals in stroboscopic mode. The control system monitors the actual lighting intervals and adjusts the pulse timing accordingly, ensuring that despite the high-speed operation required for improved throughput, the lighting intervals remain consistent and predictable for accurate image capture.
3Device complexity
If a common high-brightness LED is used for both low-brightness and high-brightness modes, then device complexity is reduced, but lighting mode control difficulty increases
Solution Approach 1:
The patent applies dynamics by implementing a control system that can dynamically switch between different lighting modes (continuous low-brightness, stroboscopic, and continuous high-brightness) using a single LED. The control circuit adjusts the duty cycle, pulse width, and timing based on the required mode, making the system adaptable to different measurement requirements while using minimal hardware.
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 approach enables stable low-brightness continuous illumination and high-accuracy stroboscopic illumination, ensuring clear images with consistent lighting periods, improving measurement throughput without degrading accuracy.
Implementation Method 1
an LED illuminating method of an image measuring device... a common high-brightness LED 60
Data Source
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AI summary
In an image measuring device that performs, on a work piece to be measured, low brightness continuous illumination and one of stroboscopic illumination and continuous illumination with high brightness, a common high-brightness LED is used, and driving circuits are switched between pseudo-continuous illumination and one of stroboscopic illumination and continuous illumination. In the pseudo-continuous illumination, an average brightness is reduced by pulse lighting. In the stroboscopic illumination, high brightness light is emitted instantaneously. The switching between the pseudo-continuous illumination and one of the stroboscopic illumination and continuous illumination may be performed by changing a lighting cycle of the high-brightness LED.