Light Guide Plate Reflection Portions for Line Sensor Illumination
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Solution Overview
Problem
Conventional dome-shaped lighting devices face challenges in efficiently illuminating an image capturing line of a line sensor, particularly when observing objects with lustrous surfaces, as they often result in insufficient light reaching the sensor and create shadows, and require larger spaces to achieve effective illumination.
Innovation Solution
A lighting device featuring a light guide plate with reflection portions and an observation window, where the reflection portions on the observation window and other parts of the light guide plate are strategically arranged to direct light towards the irradiation position, allowing the line sensor to observe the object with increased light intensity and coverage, while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a dome-shaped lighting device is used to illuminate the image capturing line, then the lighting structure can be compact, but the light intensity and distribution are insufficient especially for lustrous surfaces
Solution Approach 1:
The light guide plate is divided into distinct functional regions: a first region with a high density of reflection portions (first ratio > 2%) directly beneath the observation window for intense localized illumination, and a second region with a lower density (second ratio > 1.2 times the first ratio) for broader light distribution. This segmentation allows different parts of the lighting device to serve specialized functions, achieving high light intensity without requiring an overly complex overall structure.
Solution Approach 2:
Different regions of the light guide plate are given different optical properties through varying the density and distribution of reflection portions. The first region beneath the observation window has a higher concentration of reflection portions to create intense, focused illumination for the image capturing line, while the second region has a lower concentration for more diffuse lighting. This local differentiation of optical quality optimizes illumination effectiveness without uniform structural complexity throughout.
2Measurement precision
If conventional lighting devices are used, then the structure can be simple, but shadows are created and inspection accuracy decreases
Solution Approach 1:
The light guide plate is segmented into multiple functional zones with different reflection portion densities. The first region directly under the observation window has a high density of reflection portions (first ratio > 2%) that create intense, multi-directional light reflection to eliminate shadows on the image capturing line. The second region extends this lighting function with a lower density (second ratio > 1.2 times the first ratio) to provide broader coverage. This segmentation enables shadow elimination and improved inspection accuracy without requiring an overly complex lighting structure.
3Area of stationary object
If larger lighting structures are used to improve illumination coverage, then light distribution improves, but the required space increases
Solution Approach 1:
The invention transitions from a two-dimensional surface lighting approach to a three-dimensional volumetric lighting solution by incorporating reflection portions that extend through the thickness of the light guide plate. The reflection portions are positioned at specific depths and orientations within the plate's volume, creating multiple light reflection paths that expand illumination coverage without increasing the device's external footprint. This dimensional approach allows broader area coverage while maintaining a compact overall structure.
Solution Approach 2:
The light guide plate is segmented into a first region with high-density reflection portions for focused illumination and a second region with lower-density reflection portions for extended coverage. By strategically distributing reflection portions across different regions and depths of the light guide plate, the system achieves expanded illumination area without proportionally increasing the device volume, as the segmentation allows efficient use of the available three-dimensional space.
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 enhances light intensity and distribution to the line sensor, improving inspection accuracy and speed, especially for objects with lustrous surfaces, while reducing the required space, thus achieving better illumination without the need for larger structures.
Implementation Method 1
one surface of the light guide plate in its thickness direction is provided with a plurality of reflection portions which reflect the light from the end surface toward an irradiation position
Data Source
AI summary
A lighting device includes a plurality of light sources or a light emitting surface, and a light guide plate which light from the light sources or the light emitting surface enters from an end surface thereof. One surface of the light guide plate in its thickness direction is provided with reflection portions, which reflect the light entering from the end surface, and an observation window. A first ratio of a provided area of the reflection portions in the observation window to an entire area of the observation window is more than 2%, and a second ratio of a provided area of the reflection portions in an other part of the light guide plate to an entire area of an other area is more than 1.2 times larger than the first ratio, the other part being a part other than the observation window in the one surface.