Mobile Code Reader Optics for Specular Surface Barcode Imaging
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Solution Overview
Problem
Existing barcode readers reflect the light source on specular workpiece surfaces, causing the light source to appear in the code image, which interferes with the reading process.
Innovation Solution
A portable code reading device that uses planar light to irradiate specular workpiece surfaces, employs a condenser lens to collect reflected light, and incorporates a diffuser with an inclined shape to diffuse light, preventing the light source from being reflected on the camera by fixing the diffuser's position and angle relative to the camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light source and diffuser are placed close to each other to achieve uniform light distribution, then the illumination uniformity is improved, but the light source reflection on the camera appears in the code image
Solution Approach 1:
The harmful reflection of the light source is extracted and eliminated from the optical path by positioning the light source outside the camera's field of view. The light source is placed such that its reflection does not enter the camera lens, while still maintaining effective illumination through the diffuser.
Solution Approach 2:
The diffuser serves as an intermediary between the light source and the workpiece surface. It transforms the direct light from the light source into diffused light, achieving uniform illumination while preventing the light source itself from being reflected into the camera.
2Measurement precision
If the camera is positioned to receive specularly reflected light from the workpiece surface, then the code image quality is improved, but the light source reflection interferes with the code reading
Solution Approach 1:
The optical system uses asymmetric positioning where the light source and camera are placed at different angles relative to the workpiece surface. The light source is positioned at an angle that prevents its reflection from entering the camera, while the camera is positioned to optimally receive the specularly reflected light from the code.
Solution Approach 2:
The problem is solved by considering the spatial dimension and angular relationships. The light source is positioned in a different spatial location and at a different angle than the camera, creating a geometric arrangement where light source reflection does not interfere with camera reception of code reflection.
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 suppresses the reflection of the light source on the code image, ensuring clear and accurate code reading by focusing on the workpiece surface.
Implementation Method 1
a condenser lens that collects light reflected by the workpiece surface
Implementation Method 2
a diffuser having an inclined shape that gradually expands as a distance from the first camera increases, the diffuser diffusing light emitted from the first light source to emit diffuse light toward the workpiece surface
Implementation Method 3
a first camera that receives the light collected by the condenser lens and generates the code image
Data Source
AI summary
A light source is suppressed from being reflected on a workpiece surface of a specular workpiece. A code reading device generates a code image by receiving light specularly reflected from a specular workpiece surface of light emitted from a diffuser and diffusing and reflecting light emitted to a portion corresponding to a code. A position and an angle of the diffuser are fixed with respect to a camera such that the specularly reflected light from the workpiece surface is received by the camera in a state where the camera is in focus on the workpiece surface, and the light source emits the light from the back of a rear end of the diffuser toward the diffuser such that the light source is not reflected on the camera when the camera receives the specularly reflected light.