3D Measurement System Using Alternating Light for Stable Inspection
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Solution Overview
Problem
Current 3D measurement systems for circuit boards face limitations due to bandwidth constraints, requiring constant light sources that consume more power and have shorter lifespans, and suffer from unstable movement and redundancy in image capture, leading to inefficiencies in inspection speed and production capacity.
Innovation Solution
A measuring system comprising a base, horizontal scanning device, first and second light emitting devices, an image capture device with a telecentric lens, and a control device that alternates light projection and captures images with constant velocity, eliminating dynamic acceleration and deceleration and reducing redundant image regions to optimize camera bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant light source is used to operate the camera device, then the camera can continuously capture images, but the power consumption increases and the usage lifespan decreases
Solution Approach 1:
The patent applies periodic action by using an alternating light source that switches between on and off states in synchronization with the horizontal scanning device. The light is turned on only during the scanning period when images need to be captured, and turned off during the non-scanning period. This periodic illumination reduces power consumption while maintaining the ability to capture images at the required rate for high-speed inspection.
2Measurement precision
If the object moves relative to the optical system to shift the phase of the fringe pattern, then the phase shifting is achieved, but the movement causes dynamic acceleration and deceleration leading to unstable movement
Solution Approach 1:
The patent replaces the mechanical movement system with an optical modulation system. Instead of physically moving the object or the optical components to achieve phase shifting, the system uses a spatial light modulator to directly modulate the phase of the projected fringe pattern. This substitution eliminates mechanical acceleration and deceleration, providing stable phase shifting without the instability associated with dynamic mechanical movement.
3Productivity
If the camera captures images during dynamic acceleration and deceleration, then the inspection process continues, but redundant image regions are captured reducing the effective use of camera bandwidth
Solution Approach 1:
The patent implements feedback control by using the control device to monitor the horizontal scanning device's position and speed, and to synchronize the light emitting device's operation accordingly. The control device ensures that images are captured only during the stable scanning portion of the cycle, eliminating redundant captures during acceleration and deceleration phases. This feedback mechanism optimizes camera bandwidth utilization by capturing only the necessary images at the required rate.
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 system achieves stable and high-speed 3D inspection by utilizing camera bandwidth efficiently, reducing power consumption and extending equipment lifespan, while maintaining clear imaging without additional hardware for distance measurement.
Implementation Method 1
The first light emitting device is connected to the horizontal scanning device and is used for projecting a first light onto the 3D object. The second light emitting device is connected to the horizontal scanning device and is used for projecting a second light onto the 3D object.
Implementation Method 2
The image capture device is connected to the horizontal scanning device. When the first light or the second light is projected onto the 3D object, the image capture device captures a plurality of images of the 3D object.
Data Source
AI summary
A measuring system for a 3D object includes a base, a horizontal scanning device disposed on the base, a first light emitting device, a second light emitting device, an image capture device, and a control device. The first light emitting device, the second light emitting device, and the image capture device are connected to the horizontal scanning device. The control device controls the horizontal scanning device to cause planar motion relative to the base. With the control of the control device, the first light emitting device and the second light emitting device alternate in projecting a light source onto a 3D object. The image capture device includes a double-sided telecentric lens to capture a plurality of images of the 3D object when the light source is projected onto the 3D object.